For the true Advanced Design perfectionist, this GMC accessory should be of interest. SO RARE!
Of the few bedroll reflectors that were added by the GMC dealers, very few have survived. Over the years as the pickup aged and was given more work duties, the reflectors were a target for improper backing. After all, it was a work truck hauling even dirt and manure, sometimes backing against a loading dock at night.

These photos were sent to Jim Carter Truck Parts October 16th, 1991 by the GMC’s owner, Mike Crane of Littleton, Colorado. This ½ ton is said to be just as Mike found it at the time of purchase in the late 1980’s!
We assume the reflectors were a GMC dealer accessory because they are on a 3 window standard cab. To keep the base pickup price as low as possible, the reflectors would not have been installed at the factory. They were an easy installation by the GMC dealer with one hole drilled in the bedroll.
This small item has probably survived less than any dealer installed accessory. They were 1954 GMC only and not offered by the Chevrolet dealers. Because of being easily damaged their survival rate is almost nil!
The following photos of this original working pickup with the reflectors quite deteriorated. They were not removed or replaced as damage occurred. After all, it was for working. No one cared!

At the time of this writing in 2021, we only have two items that were used in these lights in walking by swap meet booths and looking through “For Sale” collections. Unfortunately, most old truck enthusiasts do not recognize the reflectors when they are separated from the 1954 GMC pickup!
One of these two photos show what remains of the Guide # 42 lens and the used housings after improper backing.
TRIVIA: GMC did not totally create a new assembly from scratch. The lens was borrowed from a 1954 Buick Roadmaster. Only the stainless housing was made for the GMC bedroll.

1954 Buick Roadmaster Rear Lighting