Jumpshot, I had a 2003 Silverado crew cab SRW 8.1/ Allison that I pulled a 30' TT to and from the Black Hills with. It got about 6 MPG pulling and maybe 10-12 MPG otherwise, and downshifted a lot with a load. I now have a 2007.5 Duramax/Allison and there is absolutely no comparison regarding...