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1955-59 ½ Ton NAPCO 4×4 Trivia

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.

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