Hate when I make a mistake: above post should have said "TorqueShift-G transmission which is a beefed up F-150 6 speed", not 10 speed. Thanks for not flaming me. Yes, as stated in the 3/15/21 Super Duty Order Guide, all 6.2 6 speed combinations, even in a 350 dually, use the -G transmission. While that's all you can get in a 250, a 6.2 in a 350 (SRW or DRW) comes with the choice of 6 speed -G or 10 speed. The 7.3 only comes with 10 speed. If I were the OP towing 13K twice a year, I would absolutely get the F-350, 10 speed, 3.73 since it is rated for about 4,000 lb. more towing than the 6.2. The 7.3 with 10 speed would likely get close to the same mileage as a 6.2 6 speed (and there are reports as such on line.)