I did search FIRST. However, did not fee comfortable strictly trusting a post from 2006.

I have a 2000 Bonneville SSEI with factory Bose stereo. I am replacing head unit with a Pioneer DEH-510UB. I also have a 5 channel Memphis Belle to power my aftermarket JL speakers. I want to confirm the harness I need is the METRA 70-2054.

Appreciate in advance all help provided.

If you plan on bypassing your factory amp you will need a GMOS-5 and if you are gonna keep your factory amp you need GMOS-9

I am removing the factory amp and replacing it with the Memphis Belle. I will not be using the factory wiring to go from the head unit to the aftermarket amp. I will be running two sets of RCA wires (front/rear). Another question though. I have a set of JL VR690 for my upper deck rear. Am thinking of wiring them in parallel with a set of memphis speakers for the rear doors. The amp is stable at 2 Ohms for this. Is this the route you would go, or would you forget even using rear door speakers? I am also using JL VR650-csi components for the front. Thanks again for your help.

Looking up this harness I noticed it specifically states use for retaining ONSTAR system. My vehicle does not have ONSTAR. Is this still the correct harness? Thanks for your help.

Yeah you will still need the os-5 to keep chimes, turn signals, air bags and other electrical components. If it were me, I would probably just run my rear doors off of the head unit but the amp may give it a fuller sound. I would just worry about the amp getting hot quicker. I have a feeling, you wont really hear the rear doors anyway.