Question

Convert that to a 13 and you should be good. Keep in mind though 3.42s aren't very common gears if they crap out on you. So when they go you're looking at 3.55s or 3.36s to get on the road quick. I have 3.42s in my truck I personally love them. I have pulled with 3.36s and with 3.55s they're a good combo of pulling power and fuel economy. When my gears finally go I'll probably go to 3.36s though lower cruise rpms if I don't have another set of 3.42s lying around by that time for the shop to put in.

 

The conversion is usually simple, an extra Airline and switch.

Might pick up a little mpg in the mountains.

 

10 spd 3:55 best combo for what I haul 40,000 LB or under. Max Fuel Mileage Van Flat Ref Tank they pull good UP hill DN Hill anything else is just too many variables I never had much luck with 13 or 18 spd Trans because they are made for speed

 

For a 2008 I would insist on a new DPF not just a cleaned one. Whether it was removed or not I cannot say. 2008 was the first year they were put on trucks. You might end up replacing it yourself very soon.