car radio wont work

i have a 1981 chevy camaro.i tested all related circuits and it reads fine but if install a headunit i get NOTHING. I've also tried more than one radio. Any help or suggestions? also where can i find front seat mounting brackets?

yeah id say u either a dont have a good ground, power or ign. my guess would be the ignition wire see when u put in a head unit u got two power wires really one is a constant and the other feeds the power when the key is turned over w/ out both its not gonna work call crutch field and they will be able to tell ya which color wires in your car does what thats what i did and hooked it up and it works just fine but i do have a 91 or i would just tell u the colors my self...also if u ever hook up an amp ull have to make sure to also hook up its remote wire or the amp wont work (only telling u this cause alot of people dont hook it up and cant understand why it dosent work just givin u a heads up)

id say its a bad ground, when you say you tested all related circuits, how did you test them?

The basic alligator clips to the ground test light to the hot wires. I found I had a bad ground in my trunk. A regular 8 gauge ground wire wound't support 3 amps.