Hi, I'm currently working on an '87 GT car. When I bought the car, parts of it were missing, including the radio and the radio amplifier. I bought a used amplifier off of eBay, but it won't plug in. This car has 6 speakers--does that automatically mean it has the Premium Sound system? And if so, does that use a different amp? I've been hitting up eBay nonstop, and none of the amplifiers I've seen are even close to plugging in. I really DON'T want to put an aftermarket system in this car. Anybody have any ideas on how to make a factory radio work? Again, all of the other wires are present and uncut, but the amplifier is (I assume) the only missing piece.