The "wing" or spoiler on the Fiero is unique and was not used on any other vehicle. New replacements are available from JC Whitney and the Fiero Store. Used Fiero spoilers appear frequently on eBay. Spoilers from other vehicles can be made to fit the Fiero and some will have a brake light installed in them, such as those from the '86 Firebird.
The Formula and Indy were the only models that had a wing as standard equipment. (Actually Formula and Indy were an option group on a coupe; the wing was standard equipment within that option group.) Wings were optional on GTs and SEs. The wing in 1988 was slightly different on the underside than in 1984-87, but all factory wings interchange.
Fiero wings used to be a highly desired theft target and many that were stolen were replaced with aftermarket units. Used wings were very scarce and although the original production option price was under $300, Pontiac had replacements priced at nearly $1000.
All factory wings had two separate stands (called stantions) that screwed to the underside of the wing. The stantions and the gaskets which mount between the stantion and deck lid are different depending on the year and model as follows: