More than likely you will need an adapter, or do some cutting and splicing to make it work. How do I know this?
I found a nice Pontiac radio in the junk yard that I wanted to use, and low and behold the plug on the back of this radio is completely different from the on in the Fiero.
This is the radio: (It's a full double din, but I am modifying the center console for it to fit)
Also be aware that a lot of the radios from the 90's had "anti theft". You can do some
Googling on the radio to find out how to get the code or to bypass it all together.
------------------
.
.
High Quality Fiero Reproduction Stickers are Available in THIS THREAD IN THE MALL.