stereo problems 72 firebird

I need help with the stereo in my 1972 Firebird. I have owned this car for about 15 years and have always had trouble with the stereo(s). Once installed (I have gone through three of them) they either drain the battery or just no longer power up. Any ideas out there of something I am doing wrong? Thanks for any help/advice you might have.

stock stereo or aftermarket? are you using the factory wiring harness for the radio?...sounds like the factory wiring was changed at some point to the radio and "jimmy rigged". check it for splices or cuts. also check the wiring for shorts or burnt spots. or if your not going for a "show" car that might lose points for a changed wire.....wire it yourself. find a fresh new 12 volt source under the dash that powers on with the ignition and a nice new solid ground spot. plent of both under that dash. hook up your speakers and go from there. ive seen some cars that people that didnt know what they were doing re-wired the stereo and i was amazed the car didnt burn to the ground. if those ideas fail and you want a decent aftermarket radio...take it to a good local radio shop and have them re-wire it from scratch...not to expensive...hope that helps...good luck