I have heard conflicting stories on that dura.
I have been told that the older GMLAN is the same setup as the "new" entertainment bus just slower.
My GF has a 2013 so I might just try hooking into hers first to insure it works. With that in mind is it as simple as tying the low canbus to ground and the high canbus to the entertainment bus?
How did you connect to your GMLAN port? Did you tie the CANLow to ground and CAN HI to the dataline?
Also, I have an older system that I believe is 10.5K baud that doesn't have a high speed bus.
GM added the high speed bus in 2006 and my truck is a 2003.