Were you able to find a solution?
From what I have researched it isn't a very straight forward replacement.
I'm looking at all of this right now. I bought a kenwood DDX470 so I can have iPod control and bluetooth connectivity to a phone. The goal is to remove all temptation for my son to pick up his ipod or iphone while he driving (illegal in Ontario).
One of the issues is that so many things seem to run through the GM radios that you need adapters for all of it. First, you can lose all the chimes and certain covenience features - like when you turn the car off and take out the key, the radio stays on until you open the door.
Second, if you do have steering wheel controls, they won't work without an adapter.
There is a GMOS-01 adapter that will keep all of the factory chimes, onstar and convenience features with a new radio.
There is the ASWC-1 universal steering control adapter that will connect to a radio that has a wire/input for a remote/steering control.
Crutchfield.ca has both for us in Canada, but the GMOS-01 is about $110 vs. many places in the U.S. that are about $25 less, and the ASWC is $90, vs as low as $55 in the U.S.
I've ordered stuff from Crutchfield before and the service is fantastic, so that's probably what I'll be doing.
Does anyone know what happens if you don't use the GMOS-1, and just use a regular wiring harness to get the all of the basic radio functions? What "features" do you actually lose in the vehicle?
