Wonder if it could be a late 67 and 68 thing.
I doubt it. The November, 1967 P&A shows P/N 3903474 only being used on the 68 Camaro with U57, as does the September, 1968 P&A, the February, 1969 P&A and the February, 1971 P&A. The 1967 AIM shows only the plate (P/N 7302757), where the 68 AIM shows the plate (P/N 7302757) AND
the emblem (P/N 3903474).
There's one P&A from October, 1966 that shows the 3903474 being used on the 67 Camaro, but it states it's for the glove box door, and since the 67 glove box door didn't come with an emblem, it's incorrect. Interesting enough, it says that part number 3903474 is for the 67 Camaro glove box door "exc. 350, R.S.", but it has another number (3903475
) that states it's for the glove box door "w/R.S. (exc. 350)". Looks like they were originally going to add an emblem to the glove box door in 67 but changed their minds!