This may help. I must apologize for the gross hack job done to the radio area. I'm pretty sure this was done by my brother when we were teenagers and my mother owned the car.

The flimsy metal bracket (ground strap?) should have a hole around the radio knob similar to the lighter. This was cut out during the stereo operation 25 years ago. As I disassembled the dash, I'm finding out why the gauge cluster wasn't working properly. The green wire is a ground which is not standard. I've tucked it up and left it there for the time being until I can get the dash reassembled and installed. I'll probably re-fabricate the missing hole around the stereo unless I can find a replacement for the ground strap