Headunit interface? Help

[JAYB1RD]

Hey everyone, I should be picking up an H3 by the end of the year. It will be my first new vehicle

Currently, in my old truck, I have a real nice sound system with a couple amps, components, a sub, and Sirius. It's a 1991, so all I had to do was find power and ground (I like em simple!). I've seen little to no info regarding how to swap the stock radio out in favor of my kenwood setup. I've heard there was an interface that will allow the onstar and some other things to work, but I don't know enough about these yet.

What's it going to take to get my headunit to work in the new 07 Hummer? I believe the new truck has the base model radio with XM (Build code U2K). Other codes are non-radio relevent.

Thanks!