There's at least one other thread here from not too long ago about the V-10's. They're good motors, and very reliable. The early Triton engines, both the V-10 and V-8 were prone to spark plug issues because they had aluminum heads with only about 2 threads holding the plugs in. The problem's came after the factory plugs were replaced, because they were only s'posed to be torqued to like 16 lbs - many folks way over torqued them and damaged the threads which tended to cause the plugs to blow out of the head. Even if that happens, there's a relatively simple fix for it. But some time in '01 I believe, for sure by '02, Ford had gone to like 5 threads in the heads, and the blown out plug issue pretty much went away. Never heard anything about head studs rotting off, or any other kind of issues with the heads outside of the spark plug thing.
Mileage isn't great, but also isn't nearly as bad as most people think. I had an '01 F250 V-10 with an automatic and 3.73 gears - it got 14 empty on the highway, 10 with a 20' x 6'8" gooseneck full of cattle, I averaged 11-12 as a farm truck/daily driver. It was a great truck, I loved the motor but it was two wheel drive and I couldn't live with that. I'd buy another one today if I could find one I wanted.
But all that's beside the point - the question was what will it pull. That 20' stock trailer was the biggest thing I ever pulled with mine, and like I said, you could cram it full and go as fast as you wanted. These motors make their power at higher rpm's than a diesel, so don't be afraid to wind it up a little more. I've also had a couple of the 5.4 V-8's in F-250's, and we hauled a lot of hay with them - 14 bales at 1100# each, and got along fine. We weren't trying to go fast though.
