I disagree that there is no downside to 4.30 gears. Horrible gas mileage is one. I really thought I'd be happy with short gears. If I had to do it over again I would have got 3.73 gears. My buddy has the 3.73 gears in his and he can pull a 10k trailer just as easily as me with better mileage.

 

But you know that there's no way his truck is pulling that just as easy. We seem to be going over this almost daily here. Your truck with 4.3's pulls a 10k trailer easier than the same truck with 3.73's.

What sort of mileage a are you seeing?

 

Apples to apples, taller gears net worse towing mpg than shorter gears(i.e.4.30), especially in a naturally aspirated V8 SuperDuty.

 

I'm not seeing better mileage towing with the short gears. Averaging 10mpg city and highway combined empty. 7.5mpg hauling a 10k travel trailer.

 

I would say your mileage issue is all in your driving style. I have 3.73's, my dad has 4.30's. I can get a bit better than him on the hwy empty, that's the only place I can beat him. But neither of us run up and down the interstate very much at all, especially empty. His average is 12.9, exactly 1 mpg better than mine, until I reset my meter a couple weeks ago. I was averaging in the 14's on 2 tanks of fuel, but I have become bored with trying to hypermile, and in two days, I'm already down in the mid 13's. Dad is by know means a slow driver either. In fact, he is probably more aggressive than I am.

 

My truck has 3.73 gearing. It's pulled anything I've ever hooked her up to. Expect 8 to 10mpg. Empty on long highway runs I get close to 15mpg. In town with back country roads I'm just over 11.5mpg. Don't regret not buying a diesel truck at all.