Look for a 99-2001 F350 Powerstroke. Plenty of truck for any trailer out there in the price range you are looking at. They resale on those years is under 10K for a decent truck. Things to look for, front wheel hubs, ball joints, rear pinion seal and steering gear box. These are all the things I wound up replacing at one time or another, but it was a solid truck, just too much for what I needed at the time when Diesel was $5 a gallon. I wish I had that truck now!
A few other things to look at, if the transmission has been replaced and or the PCM reprogrammed to eliminate shift flare, See if a coolant filter was added(not something done a lot, but helps a lot keeping coolant clean), and check the oil pan for rust. Early 99 through 2003 had the 7.3 Powerstroke, stay away from the 6.0 powerstroke in later 2003+ models.
