I grabbed this from another forum
Looks like someone in the Gm-Trucks forum has figured it out. I haven't tried this, but it looks promising....
http://www.gm-trucks.com/forums/inde...ic=78031&st=30
I added blue tooth from an 09 to my 07. can get you the factory gm parts to add it to your gmt900 trucks. my cost at the dealer ship with the vcim, bluetooth antenna, and new buttons for the steering wheel with phone pictures on them is about $300.00 and it will have to be programmed. then it will work just like factory 09. all you need to have is factory onstar and steering wheel controls.
here are the parts you need to add factory bluetooth to your 07 or 08, sierra silverado, yukon, yukon xl, tahoe, suburban, acadia, and enclave.
vcim # 20783877
antenna # 15938939
steering wheel switch # 25851951
As the original post suggests, I priced the parts from
http://www.gmpartscheap.com/
vcim # 20783877 - $263.64
antenna # 15938939 - $29.72
steering wheel switch # 25851951 - $27.86
No idea on shipping costs.
You may also want to check gmpartsdirect.com .
I want to upgrade my 2007 yukon xl bosse nav onstar with Bluetooth and hope it is this easy.