Not nagging here but no one has seen every one of the 20,302 '69 Z/28s built. Over at the CRG we use the phrase "normative practice" to cover standard operating practices on the assembly line. That means production was configured to process uncoated Z/28 wheels. They were furnished raw, cleaned, dipped in black primer. The face of the wheel was painted argent. Did this process apply 100% of the time? No one knows but I doubt it.
I managed service replacement parts in automotive supply chain and if production needed my parts to keep the line going, they took them. In this case they ship from the same supplier. By November 1968 Chevy had more Z/28 orders than they could build and stopped taking orders. That tells me the plants were having a hard time keeping up. If the plants needed service wheels to maintain delivery schedules, it would happen.
Now that otherwise original cars are turning up with gray wheels, it looks like service wheels may have gotten into production on rare occasion. I have seen several grey AD and YH wheels in my days and assumed they were service parts. Maybe not. Wouldn't be the first time an original car was found to have 'incorrect' parts.
