I have been looking into the 5th wheel thing myself. I bought my truck a year ago next month, and just now starting thinking about buying a 5th wheel for taking trips. This got me researching what my truck's capacity REALLY is.

I may be mistaken, but I think the GVWR is the same among all the F-250 models...6.2 or 6.7. The only difference is GCWR. The higher GCWR gives you a higher towing capacity, as long as you can keep the truck itself light. Using the calculator and truck info on the following links, you can see that once you load your truck with a full tank of gas (35 gallons), 4 full size people, and a 20%-25% pin weight ratio, your towing capacity ends up being limited to the GVWR rating, not the GCWR.

In fact, the 6.7 might actually lose out to the 6.2 in this aspect. This is because the 6.7 curb weight is estimated at 7443, while the 6.2 is 6787 (crew cab)...and thats before you put a drop of gas or a driver in the front seat.

Only if you can keep the pin weight down does the more expensive 6.7 let you tow more....LEGALLY.

Now for bumper pull, its all about the GCWR.

Fifth Wheel Weight Calculator

https://www.fleet.ford.com/truckbbas...Pickups_SB.pdf

http://media.ford.com/images/10031/2011_SD_Specs.pdf