Fender tag screws and many other sheet metal screws from the Mopar muscle car days were generic, unmarked sheet metal screws still sold in hardware stores.
i can think of many unique screws used on mopars
that are made of unobtainium unless you harvest
them from a parts car..
Of course many fasteners are unique, but as I have cataloged all 2000+ fasteners on my car for bulk restoration, I stand by what I said - there are many generic ones. In fact there are 31 other generic #8-18 x 3/8 Phillips pan head zinc plated sheet metal tapping screws in my car, mostly near the dash panel, that are identical to the generic one in my fender tag and to the same at Home Depot.