Originally Posted by OldCoot
Remember, you don't have to stay in 4th gear or even 3rd when you're in the mountains. Switching to a 3.73 or 4.10 is expensive and it will eat your lunch in gas mileage. Better to shift gears and get the benefit of the higher gear when not towing.
I did exactly that with a GMC and a 350. Went from 3.42 to 4.10 gears and never regretted it. The around town gas mileage degraded slightly, about 1-1.5 mpg, but the unloaded hiway mileage stayed nearly the same, 16.5 vs 17 MPG. There was a HUGE difference in the way it towed though. Never used overdrive when towing with either gearset, but the towing mileage actually increased with the 4.10 gears because the engine was working in a much happier place. I'll never own another gas tow vehicle with anything less than 4.10 gears again.
Dennis, Linda, and Scout the Dog
2013 Crusader 295RST
Husky 16KWS Slider
2013 4WD RAM 3500 Cummins TD SBCC