wiring
While those digrams are helpful, there is not a whole lot on there about the radio. The power connection in the dash harness is fairly standard GM. Yellow is switched power, black is ground, gray is an illumination lead that has power when the lights are on. These should all be in one connector that plugged into the factory radio. There may or may not be a connector for speakers. If your car came with the stereo dash speakers there could be a connector for that. One pair will will be a light green/dark green combo. I'm not sure about the other pair could be tan and brown. If you are adding speakers you will probably run your own wiring anyway. A modern stereo will most likely also require a constant power source, tapping into the cig lighter lead is close by. Good luck with it.