I finally found some blackouts for the tail lights that are cheaper than $90, but the seller said he's not sure if they will fit on a 91. So, I need to know if GM changed anything on the tail lights between the 1989 model and the 1990 model. Thanks.

 

not that i know of
the only things that changed over the years were the grid pattern and black stripe across the middle
not sure about the black stripe, but i believed irocs were gridded and 91-92 were also gridded

 

The seller says they fit 85-89 Camaro/Iroc Z. My tail lights are the grid pattern.

 

They will work.

 

Awesome.