Which Differential for Truck Camper

Fishcamper wrote:
I drive a 6.0L 2011 extended cab 3500 with the 3.73 ratio. Here is a very specific example of what I experienced over a 6,611 mile trip last spring. I carry a Lance 920 (about 2700 lbs, so lighter than yours, but I'm probably not much under your 4000 lbs. when traveling cross-country). In any case, with holding tanks empty but everything else loaded (including 2 passengers) it weighed in at 11,160 lbs. I'm pretty much a speed limit plus 5-10 driver.

I found the 3.10 to provide more than adequate power for this rig. Note, however, for what it's worth, the trip was on relatively flat country with no climbing to speak of.

Gas mileage experience with the 3.73:
-Cape Cod to Sycamore, IL (slightly west of Chicago) - 11.8mpg
-Sycamore to Yellowstone - 8.9mpg (staggering headwinds)
-Within and around Yellowstone on the NP roads (1,020 miles at 45 mph but with numerous stops and starts) - 12.2mpg
-Yellowstone back to Sycamore - 8.9mpg (included some city driving in Montana and again forceful headwinds. Yes, headwinds coming west and going back east! Makes me think of my Dad who walked a mile to and from school, uphill both ways!
-Sycamore to Cape Cod - 11.7mpg

That's it for what it's worth; the good, the bad, and the ugly (699 gallons of gas).

I have a 6.0L 2012 Extended Cab 2500 with 3:73 ratio also. My mileage and performance has also been similar to yours and I live in Alaska where I'm almost always crossing a mountain pass or two. I am also towing a 16' snowmobile trailer with ATV's or snowmobiles depending on the season along with the my Wolf Creek camper. 4:10's will give you a larger load capability, but 3:73 will give a slightly better fuel mileage, even with a moderate load.