I have a 34 foot gooseneck horse trailer with living quarters that weighs approx. 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. If you're not ever going to tow a heavier trailer than what you have now, the 3.73 gears will probably be fine. The 4.30 gears are awesome and only hurt the mpg about 1 mpg. I believe you will be very impressed with the 6.2 engine. Mileage towing above trailer at posted speed limits is between 8 and 9 mpg. Empty is around 14 to 15 highway at posted speed limits. Good luck