Plastic (clear) cover is the same on any 85-92 Firebird / Trans Am), so go to the junk yard and pull a nice one for a couple of $$ If there's light scratches you can polish it to make it look like new again.
Hi,
The part you are referring to is still available oe, and is referred to as an i.c. lense.It's scary how little change there was from '85 to '92, I think all years will fit. Confirmation of an earlier post!
Dale