Here is the thread with a pretty good cross reference of everything there is to know about the firebird dash:
https://www.fiero.nl/forum/Forum1/HTML/047561.html
If someone with Fiberglass skills were to build a pod like the 90 prototype it would fit in the Fiero perfectly. As the pictures below point out this cluster appears to have been designed for the Fiero and later used in the Firebird, and not the other way around.

Just to liven up this thread though is my conversion chart of Firebird to Fiero. My data shows that 93 to 98 are pretty similar, with only minor differences depending on what options you had, (6 speed, auto, TCS, etc). After 99 all bets are off, GM added more and more gauges controled by modules and completely digital. I would look for an older model with mechanical odometer. Those are pretty much guaranteed to work.

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1988 GT (Firebird Interior),1988 Fastback (4.9 Chop-top #1 of 1), 1984 Indy...Firebird Interior Installation Website
[This message has been edited by jscott1 (edited 12-08-2004).]