Just what I needed and an easy installation
2005 Buick LaCrosse
I ended up getting an incompatible GMRC-01 when I ordered everything because I didn't want to keep on-star. I thought i had done all my homework and was fairly sure my car wasn't factory amplified. Well, once installation day came, i was surprised to find it that it is factory amplified. With the GMRC-01 harness, I got this constant loud white noise hiss from all speakers even at zero volume. Thankfully, it states that you will need the GMOS-04 in the installation booklet somewhere if you have a factory amplified vehicle. Being a Saturday afternoon, I had to pick this interface up at a local big box store. I was instantly surprised by the amount of extra wires and that it already has the wiring incorporated for the steering wheel control adapter. Installation of this was a breeze and it seems to be working just fine. I only had to adjust the on-star volume on the unit I got, the other volumes were spot on.
Pros: Works well right out of the box, easy install, easy to adjust the volume levels for chimes/on-star/factory amp
Cons: GM made it necessary to use these aftermarket solutions to simply install a radio