I have the truck in my shop. This is an '06 GMC 4dr dualli, black. This is one beautifull truck. Driving it is very smooth, quiet, and feels like it has a lot of grunt . Ally shifts very nicely, the shifts are extended out a little further in the rpm range as compared to what I am used to. I had to buy a Vetronix Candi module to comunicate with this truck. You guys with a Tech 2 get ready to spend some money if you want to play. I have not done any testing on this truck yet, but will report info as I see it. I will be tearing down the Ally Monday for testing and seeing what can be done with it.
I have been fortunate to have had an '06 Dodge Cummins, an '06 Ford PSD, and now the GMC Duramax for trans mods in my shop the last couple of weeks. These new trucks are impressive and I liked every one of them. Funny they are all dualli's so I had a good comparison. My favorite hands down is the GMC Duramax. Power is better, ride smoother, cab quieter, interior more comfortable. I do not tow mind you and this is a personal evaluation. IMHO GM built a kick-a$$ truck, best of the bunch. More info will be coming soon.
mike