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Trivia

GM Odometer Trivia

Monday, December 3rd, 2018

When you check your truck odometer for a replacement, note the gear taper that turns the five numbered mileage wheels. Some have straight gears and others tapered.  Each have 15 teeth.

The rule on Chevrolet, GMC and other GM vehicles is as follows:

If the odometer gear teeth are straight cut, the unit fits below the speedometer needle shaft.

If the odometer gear teeth have a tapered cut, the odometer assembly fits above the speedometer needle shaft. The different teeth “cannot” be interchanged.

Here are a few examples:

1955-58 Floor Mat Trivia

Tuesday, August 28th, 2018

The Chevrolet Cameo and GMC Suburban Carrier came with black rubber floor mats like the other GM trucks (no carpet) except for one exception. This is the story!

The exterior of all 1955 Cameos were painted only one way! It was Bombay Ivory with Cardinal Red on the vertical post behind the door, the lower inside panels of the bed, and the five wheels.

The painted part of the interior was the same two colors in a very attractive combination together. To add one extra touch the Cameo designers added a red rubber floor mat. This total appearance package gave it just the right impression on the dealer showroom when the customer opened the door. The words “Oh my, How Nice.” That positive impression is just what the Cameo was created to do.

No pickup had ever been offered with such attractive appearance features. It is suspected this was done by the same Chevrolet Interior Automotive Designers that had created the first Corvette two years earlier.  Only white in 1953 with a combination red and white interior.

With over 5,200 Cameos sold in 1955, the red floor mats probably added very little more over black to production costs. The molds for the more traditional black mat could be used for either color with no changes.

Just like the second year Corvette, different exterior colors would now be available in 1956. There was a gradual phasing out of the red mats. The Chevrolet Master Parts Catalog (sent to the dealers about twice a year to show new prices and what parts were still available to sell them.) printed March 1957, shows both red and black mats as replacements for 1956 and only black for 1957.

Thus, from these assumptions it is as follows:

  • Red Mats continued in 1956 but in only Bombay Ivory and Cardinal Red Cameos
  • With many colors now available in 1956, a red floor mat would not blend with blue, green, etc. Therefore, these other colors received black mats.
  • General Motors did not offer other floor mat colors.
  • They did not make another large run of red mats just to be placed in Cameos with a Bombay Ivory and Cardinal Red exterior.
  • The run of red mats had come to an end, however they would be used in 1956 Bombay Ivory Cameos until supplies were exhausted.
  • A red floor mat used in the first year Cameo was a Chevrolet marketing idea. When they made over 5,200 in the first year it probably was no extra cost to make red due to high volume.
  • The GMC Suburban Carrier always used a black mat. Red was a Chevy marketing idea.
  • Carpeting was not available.

What if you really, really want a red rubber mat for your Cameo to complete the Bombay Ivory restoration?

At a recent swap meet, a Cameo owner stopping at our booth said he made his own red mat as follows:

Buy the current available black mat, remove all evidence of grease or oil stains, have a quart of red paint mixed that is made for the non-metal bumpers of today’s cars. Spray evenly on the visual areas. You now have a 1955 Cameo red floor mat with flexible paint. NOTE: No guarantee it works but he was happy with his creation.

What color red to use? Do not know. Just look at the lipstick counter of a retail store and see all the different shades of red! We can only assume Chevrolet would have chosen a shade close to Cardinal Red.

Announcing:

Tooling is under construction of the correct design General Motors truck floor mat. Yes, a replacement black mat is now available; however, it just covers the floor!

Our new floor mat will be like a NOS mat we recently found. Even the ridges are on the underside to allow air movement for quick drying from water leaks. Price will be just a little more than the current “wanna-be” mats on the market.

Surprise:

With this new tooling we will also produce a limited number of mats in red. These will be of interest to the 1955-57 Cameo owners that have exterior color of Bombay Ivory or Cardinal Red.

Strange but True:

The lowest mileage Cameo in existence is a 1958 with 1.4 miles on the odometer. It is currently in a private collection in New Hampshire.  On this Cameo, it left the assembly line with its black floor mat still rolled behind the seat.  Why?  We assumed to keep the Cameo from arriving at the dealership with evidence from muddy feet of delivery people.

1955-59 ½ Ton NAPCO 4×4 Trivia

Monday, July 2nd, 2018

During the mid-1950’s General Motors begin seeing the trend of increased demand for 4 wheel drive trucks. Not to miss a good opportunity they decided to offer this option in 1957. As it would require several years to develop their own 4×4 system plus the back road testing, GM “temporarily” used the best of the pre-existing systems. They bought kits from NAPCO (Northwestern Auto Parts Company of Minneapolis Minnesota).

Of course, the letters NAPCO were never printed in GM literature and the NAPCO fender or Cowl post chrome emblems were never attached as in a franchised 4×4 stand-alone dealership! However, GM could not eliminate the N-A-P-C-O letters that were cast into the front axle housing. They are in full view.

Owners sometimes wonder if their 1957-59 NAPCO system was installed by GM or the local Franchised NAPCO dealer (in most medium sized towns). Here are some things to look for if you would like to know:

  1. 1. A quick way to tell the source is the leaf springs. From a NAPCO installed kit the ½ ton front springs are not changed but have 6 leaves on the front. The GM assembly line used 7 leaves.
    On the rear NAPCO installed kit they used the original 7 leaves. GM used an 8 leaf spring.
  2. The mid-cross member toward the rear of the engine is riveted to the two frame rails. A NAPCO dealer will bolt these back in place.
  3. Chevrolet/GMC ½ ton NAPCO pickups came with 17.5” wheels (1957-59). The franchised dealers left the original 15” wheels as they were just adding a 4×4 system.

Prior to 1957, this system was placed on GM trucks from authorized franchised NAPCO dealers. The reader should be aware that often Chevrolet and GMC new truck dealers also became
NAPCO dealers, because this system was not available from G.M. No doubt, GM did not make an issue of this because it also added to new truck sales.

NAPCO also provided these 4×4 kits on other major US trucks such as Studebaker and Ford. This helped the independent NAPCO dealer to survive while the GM dealers were selling most
of the Chevrolet/GMC systems.

More Trivia

  • The base price of the ½ ton was less than $1,600 and the NAPCO option was almost $1,000. You were in serious need of a 4×4 when you paid ¾ of the pickup price for this option.
  • To our knowledge, the V-8 engines were not offered when the NAPCO 4×4 option was bought NEW from GM. After all, when you paid that much money for this option, you would be driving off road, extra speed or power was not necessary. Some owners might push their NAPCO beyond its limits! The almost
    bullet-proof 235 six cylinder on Chevrolet and 270 on GMC, was what was available.
  • If you see a ½ ton NAPCO with an original V-8, you can be sure it came from a franchised dealer. They would add the 4×4 to what the customer requested.
  • By 1960, General Motors had developed their own 4×4 system. NAPCO knew this was coming, and no doubt they expected the loss of their biggest customer. Their change was that now many buyers would buy from GM because they could get all in one package. This put the total purchase on a GM warrantee. If a loan was needed it was all on one monthly payment.

Valve Cover Trivia

Tuesday, January 30th, 2018

If you really like learning about old Chevy truck six cylinder history, this article is for you.

We recently visited Jerry’s Chevy Restorations in Independence, Missouri and noticed an interesting display on a side wall of his shop. Jerry has the complete series of Chevrolet “Stovebolt” six cylinder valve covers used on cars and trucks between 1937 and 1962. This 25 year display is even painted the correct gray color for trucks.

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No doubt it took much time cleaning, repairing, and painting to make them ready for their place in his restoration shop. Here is the order they were used in Chevrolet vehicles.

1937-38

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The two mounting stud grommets fit in a pocket below the surface of the cover. The valve cover must be removed to replace them. See the backside where the small metal strip secures the rubber grommet. (Not on 1940 and newer) Three necessary venting slots are on the top to allow the engine to breathe.

1939-48

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Redesigned with two larger attaching holes in cover so it is not removed to replace the mounting stud grommets.

1949-53

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New Idea: For the first time the add-oil hole is on the top of the valve cover. Now the mechanic did not add oil through the side engine draft tube. Good change! Less chance of some oil spilling as the oil container was placed down to the draft tube on the side of engine.

1949-53 – COE Trucks

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This different valve cover is used on the cab-over-engine “COE” trucks. Because the engine is under the cab, oil cannot be added through the top of the valve cover as with a conventional cab. Therefore, add oil hole is not punched but the spot remains where it is placed in a conventional cab of the same years. GM wanted no part of a gradual oil leak from a capped hole and it being so difficult to reach. The continual oil seeping would not be good for the truck owner or repeat new COE sales.

NOTE: The Chevrolet Master Parts Catalog for April 1, 1950 shows the buyer of a COE valve cover must purchase one for a conventional cab. The manual states it will be necessary to seal the oil filter hole with a thin sheet metal disc to provide clearance. Therefore, the photo in this article is of a pure factory GMC valve cover, not a modified unit altered by a dealer.

Of course, the Chevrolet Motor Division knew the chance of a protected valve cover under the COE cab would probably never need replacing. This pure COE valve cover was probably never not available!

1954-Early 55

The new high oil pressure 235 engine is introduced in trucks! Oil cap continues to be sealed as 4 small breathing slots are in a different position and are front to back on the top. This gives a place for the Chevrolet script lettering to be stamped on top. Good advertising.

Now, instead of 2 vertical studs with nuts for keeping the cover attached to the engine head, an overdue improvement is introduced. Four short machine screws press directly down on the new perimeter lip surrounding the valve cover. This presses on the valve cover gasket and stops oil leaks that occurred on the earlier design when the two studs were over tightened.

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Late 1955-57

More technology! To stop engines from sometimes leaking oil out of the 4 breathing holes on top of the cover they were removed! Breathing now occurred through a redesigned add-oil cap. It was used through the end of the series in 1962.

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1958-62

The add-oil cap is moved from the front to the middle. Because this 235 engine is tapered in its mounts to the rear and the new 1958 cars have a lower hood, GM moved it. This gave just a little more space and prevented hood contact with the oil cap.

NOTE: Because of the new center location of the add-oil hole, the Chevrolet script must be “half the size” on the valve cover top.

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Fan Blade Trivia for Most 216 Engines

Thursday, November 16th, 2017

One of the most important factors in successful engine operation is to keep the water at far below the boiling temperature. This is best done by matching the radiator with the fan blade.

On 1939-53 Chevrolet trucks there was a change in cooling fans depending on the demands the truck might have. The following three fan blade assemblies were as follows:

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15“ Diameter 4 Blades

Standard equipment on ½, ¾, and one ton. Matched with 3 core radiators.

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Before Restoration

18” Diameter 4 Blades

Placed on most 1 ½ and 2 tons. Matched with 4 core radiators.

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After Restoration

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18” Diameter Heavy Duty 6 Blade – Optional

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The Chevrolet Master Parts Catalog defines this fan “for use in low speed operations”. It was available on 1 ½ and 2 ton that would require slow moving or much of their RPM’s at idle speed.

Examples: A fire truck setting at idle speed while running the pumps to furnish water through their long hoses.

A flat bed farm truck during hot summer days. It slowly moves in a field while hay bales are loaded at almost idle speed.

No doubt at higher RPM’s this 6 blade fan would create extra wind noise under the hood but, after all, it was the price you paid to have a non-boiling radiator. (And it did the job successfully)

TEMPERARY FIX

Overheating ½ or ¾ ton? As calcium builds up over the years in engine and radiator, heating problems may surface. As a “Band-Aid” to get by for a while, some owners install the larger 18” fan. With more air passing through the radiator core, major repairs can sometimes be postponed.

1938 Chevrolet Grille Trivia

Wednesday, February 8th, 2017

This data may be of interest to those restoring a 1938 Chevy truck or car grill to look very authentic.

After the chrome plating was added at the factory additional appearance steps were necessary. The extended metal on the horizontal bars were given a satin black paint. The two outer verticals were also given this satin black coating on their visible inners.

How was the color added after plating? It is suspected the total grill was painted. Then a person could quickly wipe the black from the outer edge of the horizontal bars with a solvent. This would not require a high paid skilled painter, just a person with moderate talent and a good wiping cloth.

The single indentation in the six wider horizontal bars were given a red stripe. The attached photos of a New Old Stock, never installed grill, shows the red strip was probably added by a painter in the plant not using a stencil. There is an inconsistent look in how the red was added on this near 80 year old new grill. Trimming this total paint package results in a very nice appearance. The GM designers had a good eye!

Photos by: Nancy Russell, Columbia, Missouri

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1955 GMC Electrical Trivia

Thursday, July 28th, 2016

In mid-1955 General Motors introduced their long awaited new trucks, often referred to as the Second Series. The first half of the year 1955 (the first series)) GM continued to market the 1954 body style. They remained with the 6 volt system.

Though Chevrolet trucks made a complete change-over from a 6 to 12 volt electrical system, GMC did it different. Only the newly introduced V-8 (actually borrowed from Pontiac) was given the 12 volt system. It was the expected thing for GMC to do as the adopted Pontiac V-8 was equipped with a 12 volt flywheel, starter and generator.

GMC’s almost bullet proof 270 six cylinder was another story. They continued through the end of 1955 with their proven 6 volt positive ground electrical system that they had provided for over 40 years! After all, the main two electrical accessories were a radio and heater, so a 6 volt system continued to be adequate.

Just another area that divided the two marquis, GMC and Chevrolet, into different trucks even though they shared their cabs, beds, transmissions, wheels, suspensions, and most differentials.

Early Chevy and GMC Engine Trivia

Thursday, February 11th, 2010

Though the major cab and fender sheet metal change began in mid 1947 (Advance Design), both the Chevrolet and GMC trucks kept their same proven six cylinder engines as used in prior years.

The base engine in GMC light trucks was the 228 cubic inch inline six cylinder introduced in 1939. This overhead valve unit had a full pressure oil system with its rod and main bearings lubricated from drilled lines within the crankshaft. Their high oil pressure is reflected on the dash gauge reading 0-50 pounds.

This family of engines during the Advance Design years also produced the 248 and 270 cubic inch units. The cylinder diameter in their main difference. They all share the same overhaul gaskets, water pumps, oil pans, distributors and side plates. On GMC, not Chevrolet, the cubic inch is the first three digits of the stamped serial number on the flat surface behind the distributor.

Chevrolet’s six cylinder used during most of the Advance Design years was very different from the GMC. Its standard 216 cubic inch engine was a result of continual improvements since the first Chevrolet six cylinder began in 1929. The 1940’s 216 truck engines were almost identical to that in the Chevrolet car. Therefore, millions of 216’s were on the road by the beginning of 1947. Their basic design and easy maintenance made them one of the greats in lower priced vehicles. When used on the roads of that era, they provided dependable service both on the farm and in the city.

The 216 engine was the standard power plant in the 3000 and 4000 series trucks. Its big brother, the 235 was optional on the 4000 series and standard on the 5000 and 6000 series. It is almost identical to the 216 but the increased displacement gave the needed extra power to work trucks. The 235 truck engine was not used in pickups, however, was matched to the Powerglide transmission cars with some modifications between 1950-53.

These 216 and early 235 are designed to operate without oil lines drilled in the crankshaft to lubricate their bearings.

The early 235 should not be confused with the more famous later 235 full pressure engine first introduced in Powerglide Chevrolet cars and the Corvette in 1953. During this transition year trucks continued to have the lower pressure design. By 1954 the full oil pressure 235 became the standard of the Chevrolet fleet. It was modified for trucks by using solid valve lifters in place of the hydraulics in cars. The camshaft gear was changed from fiber to aluminum.

Okie Bushing Installation (Just Before Installing)

Thursday, February 11th, 2010

The Problem

The closed drive shaft ( on GM 1/2 ton, 1937-54) is supported at the front by two bushings. As these wear egg shaped over many miles, the drive shaft begins to move up and down. This ruins the grease seal and causes the u-joint to begin rubbing the “bell” that covers it. Thus noise and vibration!

Finally, with a bad seal, the rear differential fills with transmission grease running down the drive shaft torque tube, starving the shifting gears. The rear wheel seals then leak, the brake shoes become oil soaked, grease runs down the inside of the tires and finally the bell flies apart from rubbing the u-joint.

The Solution

Catch the developing problem early and save much expense and down time. Install what is sometimes called an “Okie Bushing”, an aftermarket, produced originally in Oklahoma. This is a non-GM repair used successfully since the 1960’s.  This is a quick, permanent fix that does not require tearing down the differential or driveshaft!

Instructions

Remove the u-joint bell retainer and slide the aluminum round bell back, exposing the u-joint assembly. Disassemble the u-joint by removing the four bolts. The rear u-joint yolk can now be slid off the 17 drive shaft splines, exposing the front bushing.

Pull out this front egg shaped bushing from the torque tube. The 1939 to mid-1950 bushing is held in place by 2 dowel pins. These must be pulled out to remove the bushing. On occasion this bushing will require a puller. On late 1950-54 the bushing was slightly enlarged to be a press fit. This will require a bushing puller. Special pullers can be rented. Otherwise, call Jim Carter’s Truck Parts at (800) 842-1913.  They have these pullers made.

Press in the long Okie bushing – seal first. Placing a wood block over the bushing end and tap into the drive shaft housing (torque tube) with a hammer.  This action will then press the other original rear bushing and seal back out of position. The new Okie bushing will now hold the drive shaft in perfect alignment, as when the vehicle was new.

The original factory advertised this as a permanent one hour fix.  This timing is optimistic but so much easier than disassembling the differential and drive shaft as the Chevrolet dealers did 50 years ago.

 

Okie Bushing Trivia

The almost bullet proof enclosed drive shaft system on 1937-1954 Chevrolet / GMC ½ tons and passenger cars (GM knew what they were doing) does have one weakness that surfaces on some vehicles, particularly after 60 years of driving.

What was once a major repair job has now been shortened to a few hours in your home garage for those with limited equipment and basic mechanical know how.

Introduced in the early 1960’s, this non-GM repair part has saved so many vehicles from being sent to the salvage yard!  The genius inventor was in Oklahoma and thus, his creation is called an OKIE BUSHING.

HERE’S WHAT HAPPENS:  After many, many miles the two large bushings that support the enclosed drive-shaft at its front end beside the transmission, may begin to change from round to egg shape.  The hidden rear u-joint yolk that slides over the splines in the drive-shaft end, begin to cause an egg shape in the top of the bushing from the years of driving.

The more the ½ ton or car is driven, the more the two bushings can become “out of round”.  The seal can no longer hold back the transmission lubricating grease. The grease slowly moves down the drive-shaft closed torque tube to the differential.

RESULTS:  The differential housing fills with grease beyond its capacity and this fluid begins filling the two axle housing.  Next event!  The wheel seals beside the rear backing plates begin to leak.  The brake shoes become grease soaked (no longer have friction to help stop the vehicle) and only front brakes exist.  The grease then slowly runs down the inside of the rear tires and also collects quantities of road dust.

Oh yes, the other sad thing is occurring! This flowing grease that has come out of the transmission and was needed to lubricate its parts.  Sooner or later, the gears and bearings here will be permanently damaged.  You now have a ½ ton pickup or car ready for its last days!

HOW TO KNOW THIS IS COMING!  When you let up on the gas pedal while on the road, you will probably begin to hear an ungodly roar but the vehicle just keeps going.  This is what is happening: After the rear u-joint yolk has allowed the grease seal to leak, the total joint assembly starts to rub the aluminum round bell that surrounds it.  This bell is so close to the turning u-joint, it takes little bushing egg shape wear to start the rubbing with noise effects.  By this time all the above is happening and it is the sound that tells the driver that the end is near!  If you suspect trouble is coming, here is an easy way to diagnose if it is close to the time you will start walking:  Remove your differential add-oil plug.  If oil comes out, the transmission is starving and your rear tires will soon be grease covered.  Do not drive this pickup beyond your garage.  The more you drive it at this point, the more parts you will need to replace.

Facts You Should Know

From 1937 through 1950, GM secured the original front torque tube bushing with two very small dowel pins.  This was to be sure the bushing did not seize on the rotating drive-shaft, and thus, would spin on the inside of the torque tube housing.  If this occurred the long term results would be a disaster!  Transmission gear oil would soon begin to seep down the torque tube to the differential as the tube begins to increase in an inside diameter.  The results: It would be the last Chevrolet car or ½ ton the unhappy owner would ever own!

To safeguard this from happening GM added the two dowel pins as insurance against this bushing ever spinning inside the torque tube.

A CHANGE IN 1951-1954:  GM increased the diameter of the front torque tube bushing to make it a tight “press fit”.  The dowel pins were then not necessary or used.

With this “press fit” in 1951-54, a bushing puller will be required!  Even after the two dowel pins removed on the 1937-50, there will be some front bushings that will still require this puller!

To remove a stubborn dowel pin, some drill a hole part way into the center, screw a fastener in place, and then pull on the screw to remove it.  Then, the larger bushing can be removed.

IMPORTANT SUMMARY:  The GM closed drive-shaft system is not second rate quality!  So many 60 year old ½ ton pickups are still using this system after 60 years with no attention.  The later open drive-shaft replacement does not have a record even close to this.  They are just easier to replace when a problem occurs.

1934-1946 Door Handles

Thursday, February 11th, 2010

The two series of exterior door handles on GM trucks between 1934-46 are certainly different yet they share a few similar features of interest.

One characteristic which seems strange today is that the handles lock the right doors only, not on the left. This occurs on GM trucks from the early 1920’s to about 1959. At this time, we have no reason for this feature. Maybe it kept the driver from standing too near traffic as he locked the door!

The 1934-38 handles are the same. The left has no cylinder key but the right handles are the locking style. Yes, the right and left handle will interchange but this is not the way it was done by GM. Switching handles would prevent the right door from being locked. There is no inside lock on the right!

With the introduction of the new body style in 1939, the handle design also changed, however the locking and non-locking handles remained in the same position. The big change started in 1942.

GM decided that rough roads plus freezing in the North caused too much lock breakage. The die cast lock parts inside the handle were too easy to break. During that year, the lock was moved down into the door skin. Both right and left handles became the same non locking design. The following photos show this big change in door locking on Chevrolet and GMC trucks.

Door Handle Trivia

The locking key cylinder used between 1934 to 1941 is the same despite visual changes in the handle body. Of course, if the truck is right hand drive, all is reversed!

1934-1938 Right

1934-1938 Right Door Handle

1939-1941 Right Door Handle

1939-1941 Right Door Handle

1939-1946 Left and 1942-1946 Right

1939-1946 Left and 1942-1946 Right Door Handle

1942-1946 Right

1942-1946 Right Door Handle (lock in door skin)

Buy Parts for 1934 to 1946 Trucks

 

Radio Trivia

Thursday, February 11th, 2010

  • Push buttons were discontinued at the end of 1953 and did not reappear until 1967
  • Prior to 1959 radios used mechanical vibrator tubes. They would operate with either positive or negative ground. A low buzzing sound could always be heard from the tube area before the radio warmed up, once the sound began, the speaker made the buzzing difficult to hear. In recent years a major change has occurred. Vibrator tubes have been gradually replaced with a modern solid state style These are ruined if the battery is reversed. A positive ground tube cannot be placed in a negative ground vehicle
  • The 1947-1955 four staff cowl mounted antenna could be extended almost four feet. This helped pull in at least one station in rural areas
  • With a totally redesigned dash in 1954, the radio was given a major change. It remained AM only but with push buttons discontinued, it became almost half the size of the previous model
  • From 1959 and older, GM truck radios had two lead wires. One usually attached to the headlight switch so the dial light went on with the dash lights. The other wire attached to a 20 amp fuse and then to the ignition switch “hot” connection
  • The AM-FM radio was first available in GM trucks in 1970, not in 1967. These units have one sound track and are not stereo
  • In 1947, with the introduction of the Advance Design body style, GM trucks for the first time had a place in the dash to install a radio
  • In relation to wages, early radios were very expensive. A 1949 radio had a retail price of about $74.50 when it was difficult to carry $5.00 in groceries
  • The dash on the 1954-1959 GMC and 1955-59 Chevrolet has no place for a speaker opening. Thus, the factory speaker is placed between the sunvisors above the windshield