So below is the mileage I got with the 2500HD with 4.10 gearing. Keep in mind that this was mostly city driving. I don't have any longer highway only trips coming up soon but I can update you with that mileage soon. Also this is non towing mpg.
Thank you, no doubt city driving kills the mileage. I am selling a 3500 Duramax and after the truck hit 12,000 miles the fuel mileage increased about 2-3 mpg. I suspect this is a combination of engine break in and the computer parameters changing.