The F-350 Single Rear Wheel is less than $1000 sticker price over the 250, and gets the higher payload ratings.
Now, the actual truth of the matter is, other than the higher payload rating and a 4" rear axle block vs 2" in the 250 is what you get for the additional money. Everything else ends up being the same on a properly equipped 250.
The cab and bed are the same. Same frame. Same engine and transmission. Same axles. Same brakes. Same wheels and tires. Same accessories.
Where the sticky issue us is the springs, the block and the sticker that lists payloads. The sticker does not help payload nor does the block. But, if you have or find a 250 properly optioned in the spring area, they can end up the same as a 350.
My 250 has the optional camper package and ended up maxed out in the spring department... VB code springs with sway bar and rear overloads, and the same as I would have gotten with a 350.
Now, had I known what I know now, I would have spent the extra $500 in 2001 for the sticker and block, and the legal capability to pull the weight I pull. As some have said, it's very easy to go over the ratings on the F-250. For my model year, 8800lbs was the GVWR.
The first ticket is unloaded.
The 2nd is loaded with the TT and ready for a week. I think I need to tighten up the WDH and put some more weight up front.