Is it correct that GM put only 4.10 rear ends in the 2500hd's with the 6.0 engine from say 2001 to 2006? What average fuel economies are people getting? I am looking to buy a used one and had it in my head that I was going to buy one with a 3.73 rear end.

 

You can expect around 13-15 on the highway. I don't bother watching it in town. I have a hunch that your oil makes a difference - changed from 10w to 5w and went from 13 to almost 16 in the same driving conditions. I know I have 4.10 and I think that's all you'll get off the 6.0