We just bought a 2010 Jayco Jay Flight G2 Series 32BHDS. GVWR is 9750 and GAWR is 5000 and Jayco says the weight is 7765. So we are looking for a good, used vehicle to pull 10,000 lbs. We are opting between 2001 FORD EXCURSION LIMITED 2500 6.8L V-10 3/4 chassis 88000 MILES vs. 2004 Chevrolet Suburban 2500 4WD 8.1L V-8 3/4 chassis 160,027 miles.
I have a 2004 'burb with an 8.1. It's great for what you're doing.
Evaluate your truck requirement based on your trailer GVWR of 9750 lbs. You plan to tow in the West so, with a gasoline engine, you will want a tow vehicle with a tow rating of 20% more which would be 12,200 lbs. [Un-turboed gasoline engines loose 3% of rated HP per 1000 feet of altitude. Diesels being turbo-charged, do not pay this penalty.]
Carl the problem in this particular case is that the rating for the 3.73 is based on the limitations of the transmission, not the limitations of the engine. There is no reason to derate the transmission for altitude.
The 3.73 will be marginal at best out in the high country of the West.
While I have the 4.10 I have driven the same power train with 3.73 gears and can state with confidence that it is quite sufficient. With the 4.10 and my 8,500 pound trailer it is occasionally necessary to put the transmission in 3rd gear rather than drive to avoid excessive shifts. With the 3.73 it is almost always necessary except in the flatlands.
That said, the mileage on the Burb does make me a bit leery. 160K is lot of miles on a gas engine.
Again, while true in the abstract, the particulars of the situation auger differently. The 8.1 has an easy life in a 'burb even in one that spends a good deal of time towing. Mine has 160k and is not showing any indications of wear other than a leaky main seal -- compression is strong and other than what I attribute to the seal leak it only uses around a quart of oil in 2,000. Big blocks do that when new. These things put out 1100 horsepower in marine applications and are dialed back to under 400 in a 'burb. Even in a workhorse chassis they last a long time.
The transfer case is the weakest link in the power train on these vehicles. It's a $2k repair at an independent shop.
As with other 3/4 ton trucks with that kind of mileage it's not unusual to have to do some transmission work and replace the rear axle seal at some point particularly if the service history is dodgy.
The 8.1 has an external oil cooler and the rubber hoses that go to it have to be replaced every so often. It's a $600 repair at the dealer, I did it myself for a quarter of that but it's more than most people would want to try.
I get 8 mpg towing and 13 mpg with just the 'burb. Sure you can do better with a diesel. I didn't think the upfront cost and lifetime repair and maintenance cost made it worth it. Maybe the math works better for other people.