There should be a plug you need to disconnect which feed the power and speaker wiring and then the antenna wire pulls out and then the bracket that grounds and holds it in place.Then the knobs and dials.You probably need to remove the ashtray and ashtray mount to get it out.
David
http://FirstGenFirebird.org/show/closeup.mv?CarID=571 If i don't get this car back on the road soon i'm gonna go postal! On a quest for FGF knowledge 1968 Pontiac Firebird Convertible 1969 Oldsmobile Cutlass "S" Convertible *Sold*