Ok, lets discuss everything this guy did wrong....
I think it might require its own thread, like, why was the ass still in the right lane when he started losing speed? I hate amatures! Ignoring coolant alarms putting that truck on the trailer backwards, running the shit out of a hot engine till the limp mode kicked in. Yah, he was trying to keep up with the Dodge but DAMN don't kill the truck.
I ran my 6.7 Cummins 6 speed auto across 40 from one end of tn to the other at 70 down hill 65 up hill, watching my coolant like a hawk, it never went higher than 10 degrease above average (cant remember what average was on that truck. this is a 8300lb truck pulling a 6000lb trailer with 11,000lb's of freight. My plate was for a gross weight of 26000lbs and I was typiclly 200-300 lbs over that. I almost never used over drive.
word to the wise watch out for recalls on that 6 speed we had it in the dealer for one problem 4 times, part of it was the mechanic part was recalls, started with the pan leak, then they changed either the input on the trans or the rear main on the engine, then the trans sucked the seal around the shifter in and THAT was a bad leak. As far as the motor goes we had a programming recall and picked up an extra 2mpg (12mpg @ a gross weight of 25000lbs running 65 in ohio) pulling something somewhat aerodynamic gets you even better fuel economy.
if you want a top of the line tow rig the Cummins makes a nice motor, and the MegaCab is built to comfortably sit 5 people and still pull a goose neck trailer like its not there.
All diesels are expensive to fix, its a diesel thing. Guys swear buy the Dmax, some guys with Cummins decided to trade the Dmax for the Cummins, and ford guys, well, they are Ford guys.
the Duramax and cummins are pretty close in performance, right now, the 24v are by far the loudest, the 6.7 and duramax you can hardly hear run, and the 6.7 Cummins wont blow black smoke, but, you do have to use the USLD or the cats will get plugged, yes, the 6.7 has 2 catalytic converters, and they have sensors so the truck knows how much back pressure is on the exhaust.
The last big plus of the 6.7 is the exhaust brake, its not adjustable but when you slide it into towhaul and turn it on you don't need to bother with the breaks going down a grade, it WORKS.