if you have a 2008 truck ecm your going to need a trans controller. In this instance its proboally easier to feed some bogus info to the lt1 pcm for shift control. Honestly though this is one of those situation where converting to a full manual shift valvebody in the trans might be a good idea.
The other option is to use 2008 avalanche or 1500 2wd pickup trans controller and reflash your pcm to the 6.0l code if you opto to do the delte on the DOD and VVT.
The other option is to use 2008 avalanche or 1500 2wd pickup trans controller and reflash your pcm to the 6.0l code if you opto to do the delte on the DOD and VVT.