I just replaced the factory unit in my '98 w/premium stereo. The amp is in the dash, you can see it when the radio is removed, it's sort of behind & below the climate controls. The harness you need to bypass plugs in at the bottom, which if you look under the dash towards the middle near the console you can see the bottom of the amp & the plugs. The amp in the rear is for a sub in the Mach system.