Alton! Cool!!
Welcome to the forum.
You can use all of the 4 spd clutch system parts except the slave cylinder. Use the one that matches the tranny. The axles will work fine. Rodney Dickman sells a changeover kit that will allow you to use the FWD Getrag in the Fiero. This is necessary because the Fiero shift and select cables come at the tranny from the front instead of the rear.
Careful with the flywheel. 88 2.8's (I am ussuming you have a V6) used a neutrally balanced flywheel. Make sure that is what you are putting on the engine. You can use the Fiero flywheel and Getrag clutch with this tranny.
You will need a 5 speed shifter, though. The Cavalier shifter won't work because the cables are on the wrong side for Fiero.
Good luck!!
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1986 SE 350 V8