You mean the spoiler or the car ?
The story goes that spoiler was homologated w/NASCAR so they could be used on the cars.
The spoiler would have a part #, but I'd doubt they were assembly-line-installed.

As for the cars, by that time the competitive builders were cutting them up from shells and a lot of fab work was done.
They weren't quite "panel cars" then, but were significantly modified, and not very streetable, likely no VINs.