wire harness

Thought I'd shoot this question I have. I Found out last night that my Orig Stock Radio harness/connector that goes into the backside of the radio itself was cut out of the harness from my car. Does have a Factory harness to sell? Are the connector designs the same from a '78-79-80 to 81+? Cars...

The speakers, fuel gauge, and horn have a missing ground. The radio works but speakers don't when connected to the car. When I connect it to a external power source of the same voltage both radio and speakers work fine. Fuel gauge is the same way once I add an alternate ground it works properly...