I have 2 2500 Duramax's.Both have ample power with heavy 7-8K trailer. I get around 9.8 mpg from Va to Colorado, Teller County, including over La Veta Pass west of Trinidad. Either will pull it at 45 with out overheating. I'd recommend Airlift airbags on the rear and Firestone Ride rite Shocks on the front. Takes the jump out of Ia-Co Bridges. Had to reman a Duramax to the tune of $12,000 due to Garrett Turbo bearing failure. Otherwise I'm happy with them. We own a farm and have 1 of 4 trailers hooked on a lot. This week I'm going to De. with the TT, coming home and hauling 3 loads of round bales about 20 miles. Avg ety is 16-17 depending on the road and the faster I go the better mileage it gets. At 75 it will get 19.
My friend says hill will pass anything but afuel stop.
