newbie

[AGMAN]

I am considering purchasing a 07 3500 crew cab 4x4 (single axle) with a 6.6 and auto trans. (not Allison) It has 71,000 miles on it. I have read that the 07 gets less mpg than the 04-06. How much less? Is 3.73 that standard rear axle ratio? I plan to tow a 26-30 ft fifth wheel rv trailer.

[More Power]

I am considering purchasing a 07 3500 crew cab 4x4 (single axle) with a 6.6 and auto trans. (not Allison) It has 71,000 miles on it. I have read that the 07 gets less mpg than the 04-06. How much less? Is 3.73 that standard rear axle ratio? I plan to tow a 26-30 ft fifth wheel rv trailer.

Welcome to the board! All pickup trucks equipped with the Duramax 6600 have an Allison, if they are equipped with an automatic. The Duramax powered vans got the 4L80-E.

I'm assuming you're considering a new body style truck, which first appeared halfway through the 2007 model year. If so, it is equipped with a Diesel Particulate Filter (DPF). The DPF systems do produce 1-2 mpg less fuel economy, but a lot depends on how the truck is driven. Those who drive mostly on the freeway/Interstate don't see as much difference in fuel economy as those who drive more locally.

The 3.73 rear differential ratio is the only ratio offered in the Duramax/Allison equipped 2500HD/3500 series trucks. This'll do well with your expected trailer weight. ;)

Jim