Wow. It's amazing what 650 lb-ft of torque can do for you. I towed about 9000 pounds behind a 2008 Ford F-250 Super Duty and I could hardly tell it was back there. Even crossing the mountains in Virginia and West Virginia, the truck had more than enough power and easily maintained speed up hills.
I towed a 1989 Ford F-250 down to South Carolina to trade it for a 1965 Willys pickup. The Willys is in decent condition and runs very well. I plan to drive it for a few years and then restore it once some of my other vehicle projects are finished.
With temperatures ranging from 70 degrees and foggy to 102 degrees and sunny, the tow rig got quite a workout. The most amazing part was how easily the truck maintained speed with a load and how quiet the rig was at speed. Unless we were climbing a hill, we couldn't hear the 6.4-liter diesel engine. The seats were very comfortable, even after 18 hours of driving in a day. Fuel economy ranged from 9.7 to 11.6 mpg, depending on the load and speed we were running.
My dad came with me on the trip to help with the driving and lend a hand in the event of a disaster along the way. Since we came prepared with tools, a spare tire for the trailer, and a plan of attack, nothing went wrong. The only issue was a temporary electrical glitch that caused us to lose trailer brakes. After turning the truck off and reconnecting the trailer wiring to the truck, everything went back to normal. This took a total of about two minutes.
I always knew the modern heavy duty trucks were incredibly capable, but I never fully understood how incredibly easy it could be to tow such a heavy trailer. I once towed a 1988 Jeep Grand Wagoneer behind the 1989 Ford F-250 and it wasn't anything I'd like to do on a regular basis. Diesel trucks have come a long way in 20 years and the results are simply incredible.