Welcome from south GA. The worst truck I ever had was a late 70s F350 DRW , so when I started looking for a truck to pull a 5er with I was extremely surprised to find myself buying a F350 SWR. In 2015 it out-speced both GM and Ram. After 80k miles and 30k pulling a 3402rl, I am very satisfied. Today all three models offer pretty much the same hp, torque, transmissions, and accessories so test drive and make the best deal you are happy with. The engine brakes are great but DO put disc brakes and g rated tires on that new trailer if it does not come stock.
Frank and Marilyn
2014 3402RL, Sailun S637/Disc Brakes
2015 F350 CC LWB SRW 6.7L PSD FX4