2500hd rear end ratios

[sqdqo]

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.

[1st Synthetics]

If you have a 4.10 the 3.73 is going to give you better mileage. Here is a list of what came on 2003 trucks:

Differential, American 8.5 ring gear Rear..........4.2 pints
Differential, American 8.6 ring gear Rear..........4.2 pints
Differential, with 10.5 ring gear Amer Rear..........5.5 pints
Differential, with 11 ring gear Dana Rear..........8.4 pints
Differential, with 11.5 ring gear Rear..........7.6 pints
Differential, with 9.5 ring gear Amer Rear..........5.5 pints
Differential, with 9.75 ring gear Rear..........5.9 pints

Here is a thred you may want to look at:

http://www.gmtruckclub.com/forum/showthread.php?t=13928