Hey CMNTMXR57 I notice in the BS thread you were talking about bad fuel milage with your 8.1. Just what kind of milage do you get? I have an 01 155"wb GMC Savana 3500 with an 8.1 that I use for a service truck. It weighs 9300lbs. and I get 10-11 mpg in town and 14-15 on the highway. The only thing I've done to it is Hypertech programming. I also ordered 3.73 gears hoping for the better fuel milage as there were no ratings for it.