While doing some guage cluster work on my bird, I noticed that there is a panel that is in place of some buttons. The panel is in the same piece that the defrost and hatch controls go on. There are wires behind the piece, but alas, no buttons. What would they be for, if my car had it?

 

Not having a Firebird myself, I'm trying to remember where those buttons are located(Bottom of dash just below guages?),I have a friend with a firebird and upon a recent visit to a junkyard we stumbled on a firebird that had a factory subwoofer in it(rotting in the backseat) and on the dashboard where he had a filler plate (dummy button)is where the activation switch was for the subwoofer,I wonder if this is what you are refering to?

 

That's what my 86 has in that spot--factory sub woofer button that has a slide on it.
Next to that is the rear defrost and power hatch buttons.

 

On my 88 GTA, that is the factory sub switch with the gain control.