2011 F350 Lariat 4x4 DRW Crew Cab with 6.7L diesel. 400hp and 800ft/lbs of torque. Smooth, silent and VERY powerful. Doesn't even break a sweat. The difference between the 2007 (rated at 325hp / 572ft/lbs) is absolutely night and day. The 6.7L will stay in 6th on cruise without even unlocking the torque converter clutch, compared to the 6.0L unlocking, then downshifting from 5th, to 4th and in some cases even 3rd!
Also, the fan clutch used to engage on almost every hill with the 6.0L, but I have only heard it once on the 6.7L. Both trucks were in excellent mechanical condition (I was a professional mechanic for a bit over 20 years) and towing the same trailer on the same route (Fort Worth to El Paso).
Also, so far the newer TV is getting about 2 - 3 mpg better, both towing and unloaded.
Sorry, to the OP, I'm not trying to hijack this thread and I'm not saying that an F350 with a 6.0L won't pull the Columbus 365RL. It certainly will. But I can tell you that the difference in towing between the 6.0L and the 6.7L is undeniable and impressive.
Our 2007 TV:
Our 2011 TV:
Tina + Dutch and Bell, Bobo, Harley, Buddy (the dogs)
2011 F350 Lariat 4x4 DRW SuperCrew 6.7L (B&W setup w/Air Lift 5000 Ultimate)
2014 Columbus 365RL (Airflex and Voyager package)
Nights Camped 2014 - 154
, 2015 - 32, 2016 - 4