Just picked up my new '05 Duramax last night:cool2:
Specs: '05 GMC 2500HD CC D/A. Traded in my trusty '02 6.0L 2500HD which was an extended cab. I felt I had to make the jump since my wife is pulling a horse trailer 3-4 days a week and the 6.0 was only getting 8-9mpg. Hopefully this thing will do better and last longer.

I will say that it's fun to drive though:ro) . Can't wait to get it broke in and start pulling with it.

Good Luck!

I wish I would have saved the 7k on the dmax because my mileage is no different towing. But hey GM customer service says it's OK.

I think I got about 11-12 pulling about a 15K# 5er from NY to MO. When the trailer was empty (7500-8000#) and I poked along at 50 or so, I got about 16.