It’s 1966 and the new requirement of the US Department of Transportation becomes law. This requires all new cars and pickups to be equipped with backup lights. Though this may have been for safety (warning a passing vehicle that a backing vehicle is in reverse mode) it created extra expense for vehicle manufacturers. Those that had already designed their future vehicles with this new law in mind had to sometimes make a major taillight change.

For the Chevrolet / GMC step bed pickup minor new tooling was needed. It was the last year for this design step bed rear fender (had been used since 1955) and GM used a less expensive method with little more the punching a 3 9/16” dimple in the rear of each fender. See photo

This allowed the round back up light to be shining at the level with the pavement.

Most interesting!

The light assembly fit exactly where the dimple had been pressed. So much money was saved by using the park light housing from a 1955-57 Chevy truck parking light. “They already had the tooling to make it again.”

They designed a clear plastic lens to give out more light and the assembly was ready to attach to the rear fender dimple on the assembly line. This lens has the following letters that were in the mold.

GUIDE 1T ---- SAE R66

The “66” is the first year Guide made and sold this particular lens. In this case, it was also the last year of production, as later years had them installed at the factory.  

Next surprise!

GM decided that a good selling accessory would be back up lights for the pre-sold 1960-65 step beds. They could be sold by the GM dealers to their prior customers as a kit. This would include the clamp on steering column small box with lever, the wiring harness, a fuse, and one or two light assemblies to fit on the rear of the intake pockets. See photos.

This accessory required GM to only make one flat bracket. These were easily attached to the stake pocket. No tooling required! Just a stamped flat steel bracket. Surprise! On one end they secured this 1955-57 round park light housing mentioned above with the redesigned lens! American Ingenuity.

See below: