Looking to change out my Bose system in my 2000 Jimmy without OnStar, and not sure what is involved. There are a lot of adaptors available, and not sure which ones I need. Looking to replace the head unit (mine keeps getting an ERR, and front door speakers (passenger side is blown) maybe the rears, and adding a simple sub/amp. I would prefer to keep the steering wheel controls too, but not sure if that is possible with the other adapter I need. Anyone know what there is to it?