I think I have a complete set of four instruments for a 71 cougar xr7-- I purchased it over 15 years ago as a back up for a restoration project, and haven't needed it. If the dash configuration is the same in a GT as the xr7, let me know and I'll come up with a price. I'm on the east coast.
Air filter elbow duct.
Rear chrome ashtray top, or whole assembly.
Non XR7 glove box door.
Black dash pad.
And an era correct, aftermarket, tach to clamp on the steering column. An old Sun?
Let me know if you have any of these.