You probably won't make enough money to justify it. Having said that, if you really want a 1 ton dump truck, I'd look for a '99-2003 ford superduty. On the 4x4's you have to keep the front brakes in good shape - a warped or irregular front rotor or break caliper that's not applying uniform force to the rotor will take out your front unit bearings in a hurry, but other than that, they're great trucks - diesel or gas.
Hauling a load or hauling itself, the 7.3 diesel will get between 16-20 MPG in decent shape. Stay away from the 6.0, 6.4, or 6.7 unless you like poor fuel economy, high maintenance costs and poor reliability.
Having a number of diesels I disagree with coaledsweat. I've had an early 7.3 idi non-turbo and I have a '99 7.3 powerstroke and the diesel engine hasn't cost me anything additional in repairs over the life of the truck, with the exception of a blown turbo at 200,000 which was my own fault (truck pulling and overboosting stock turbo), the only things I've had to replace that were engine related in almost 300,000 miles is an o ring on the fuel filter bowl (ULSD created) and two or three cps's which is now fixed by an updated (and cheaper) part. My 7.3 IDI was super reliable, simple and parts were dirt cheap. My 7.3 powerstroke hasn't let me down at all and I know guys with the 5.4 and v-10 gassers who've had FAR more problems in less miles as well as having the engine worn out and tired before 200,000 when worked hard. My father is aproaching 500,000 miles on his '99 7.3 powerstroke and has original injectors, turbo, everything- only the IDM and the fuel filter bowl o ring has been replaced. Both my father and I are on our second transmissions (4r100 auto) and opted for HD rebuilds that should last for many hundreds of thousands of miles; we each got slightly over 200,000 miles out of the stock one - even though both our trucks were chipped with 80hp min and occasionally hauled heavy loads (air bags and truck+ trailer occasionally grossed 24,000lbs).
My nephew runs an oilfield services company in east texas/louisiana and they ran a number of diesel trucks, now, after heeding my advice and having many problems with other makes/ models, years of trucks, they run 99-03 7.3 powerstrokes exclusively and have greater reliablility. Those trucks are regularly hauling over 30,000lbs and are worked HARD. With EGT gauges, air bags, and a built 4r100 (BTS Arkansas) they have yet to have any major problems.