
Originally Posted by
simbah
If you wish to keep your Monsoon amp then you will need the GMOS-04 adapter. If you decide to go the aftermarket amp route then the GMOS-01 is the adapter you will need. Regardless of whether you have Onstar or not. If you decide to get another factory radio then you will have to have that radio programmed to fit your car at a Dealership about $75.