I read these posts often and get a lot of good info from them so thought I would share this info with you guys. Just completed a 2600 mile trip with my 08 F 350 King Ranch Long box crew cab everything stock toe boss pkg 5600 miles on it. I pull a 33 foot fiver that weights in at 13,500 lbs with a pin weight of 2000 lbs. I have the back of my truck completely built in with 3/4 plywood boxes etc with a 2500 lbs of equipment in them. I am a winter snowbird from Cdn I live in Edmonton Alberta and winter in Apache Junction Arizona. I left home and traveled through BC Rockie Mountains to Osoyoos BC American Border then into Washington thru Oregon, Idaho ,Utah ,Nevada and I am now spending a couple of days in Kingman Arizona. I kept detailed milage charts etc and I averaged 8.9 MPG that is with head winds tail winds over mountain passes some severe over the Hoover Dam which is also severe grades etc. I passed many Dodges and GMCs and was also passed my many of them, My avg speed according to the GPS was 57 miles per hour of course depending on the terrain etc. My normal speed was 65 MPH. I have nade this trip 4 years now and I never felt as comforable as I did with this truck. Regardless of the grade I kept the RPMs up and my speed never fell below 50 MPHs. I did not notice any difference what so ever in gas milegae between 60 and 65 mphs in fact the truck seemed to like it better at 65 MPH.
Problems:: I did experience a slight drive line vibration while taking off in first gear. I stopped into a ford dealer and they ordered in a shim kit and placed one shim in the main drive shaft center bearing which took out most of the vibration. They gave me the remianing 2 shims and suggested that if the vibaration was still there to have another dealer install a second one. The only other concern I have is I believe this truck down shifts to soon while in tow haul mode some times I only have to touch the brake once while decent a grade and it kicks down which elavtes the RPMs to over 3000. I am going to get this checked out when I get to AJ Arizona.
Anyway just though I would pass this on Ihave been towing fifth wheels for 15 years and never had a truck that felt like it really enjoys what it is doing like this one.

 

Nice report Hawkes, very simular to mine towing 16650# 2000 miles this summer 8.726 mpg. Loved towing and can not wait for 3,000 miles next summer. This truck was built for towing.

 

I agree with the downshift..

 

On an average it does pretty good down shifting, but like you said sometimes it jumps down too much and revs. I just hit the tow mode button and take it out for a few seconds and engage it again. Found near the bottom of hills I would take it out to let it build just a little more speed to go back up. One time though I had to stop in a panic stop. Coming down the Pocono Mtns in Pa a BMW spun out and everyone was locking up on the brakes on a steep downhill. I was amazed at the control and how fast it slowed down. The Transmission really helped keeping it in control. On a wet road might not be a good situation, it could lock up the rear end and slide. Unless the anti lock brakes take over, not sure on that one.