I love my truck! I have an 2001 Silverado 2500HD with the 8.1/Allison. The truck lives between 1000-2000rpm's and pulls like a frieght train. When I bought the truck I drove my old 78 Chev 3/4 w/454 down to the dealership with a trailer. I hooked the old truck and trailer to the new truck and towed it home like nobodies business... It also pulls my race car and buick up mountains at any speed I desire.
You will not like the gas mileage though. Best I ever got on the highway was 12mph, and around town I get between 6-8mpg.