My CD player in my base radio is jammed and the paint is chipping off one of the memory buttons, so I think it's time to replace the radio. Should I go with aftermarket or just get a stock one from the Web? Would I be able to get the one with the navigation and touch screen (i.e. is it the same connector as the base radio?)

 

Welcome to the forum.
I doubt the connectors match between the base radio and the nav radio. Personally I would steer away from the GM nav radio because their early systems were rather sketchy. I think you'd find a Garmin to be a better alternative if you need an nav system. You could check with Crutchfield to see what aftermarket radios are available and they can also provide connector adapter harnesses.