You must be right. I wasn't able to find anything that mentioned these kind of wheels as an option. At least, not a factory option. I was under the impression that these were the original wheels, but I guess not. Unless they were put on the truck by the dealer...again, maybe not.
GM was not making 6 lug rally wheels yet in 1972. Some one installed them later on after it left the dealer. Not a big deal. They are a VERY common "upgrade" on the older trucks.
Martin



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