[ChevLoRay]

Look at the installation instructions. It will tell you what you need to know and what you need to connect. Basically, these late systems need 12V, switched. It needs a good ground. Then, you'll need 12V that is constant, meaning it isn't switched. That unswitched voltage is used to retain the memory of the unit. Without it, you'll have to reprogram it every time you turn it on. Beyond that, there's a wire that powers a power antenna...you may not need that one. Then, there are wires for each channel, positive and negative for each of two or four channels.

Bottom line: You shouldn't give any thought about how the previous radio was connected. You need to know what each wire you're gonna connect, is connected to. As for a harness to adapt a late radio to the original wiring, just know that the original radio had 12V, a ground and a short harness that connected the speaker to the radio.

The antenna? It's a no-brainer.