jk96: Thanks for the link to 6.0 PS info. Interesting, but I'm not sure how much does or does not apply to the 6.4 L 2008 version.
No problem. While I don't know for sure, I would assume that the 6.4 is the same. I can tell you that I pull loads regularly in the 10-12k range with my 05 F250 powerstroke and am amazed how well this truck handles the loads. It has the integrated factory brake controller. With the combination of the brake controller and torqueshift, the truck handles great. Most of the time going down grades I barely have to use the breaks. Also, I had a guy pull out in front of me on a two lane hwy last fall. I was going 55 with a pretty good load and am still amazed at how quick and controlled I was able to slow the load down.