I have a 34 foot gooseneck horse trailer with living quarters that weighs 14,000 lbs that I pull with a 2013 F350 Dually CC with 6.2 engine and 4.30 rear end. Truck pulls this trailer with no problems - traded a 2006 6.0PSD F250 for the 6.2 gas engine with no regrets - I pulled the above trailer with both trucks and both pulled it equally well- you just have to learn to keep the gas engine in the higher rpm ranges. I had to order my F350 DRW as I wanted a 2wd with 4.30 gears with a gas engine - odds of finding that combination on a dealer lot is slim to none - I calculated the breakeven at about 150k miles when purchasing new gas vs diesel truck with gas avg mpg at 10 and diesel avg mpg at 15 and diesel at $.50 higher than gas, but it's higher than that now. The extra $8300 for the diesel engine plus the added maintenance costs makes it hard to justify one these days unless you tow almost daily. Good luck finding what you want.