The fuel bill w/ a V-10 in that vehicle is insane, but it also makes them almost worthless on the used market so you get thousands of dollars towards gas when you pick the V-10 over the diesel. The other part of the equation is that the diesel is just a lot better engine for towing, more bottom-end torque and runs cooler, etc..
Avoid the early ('03-'04) 6.0 diesels at all costs. Get the 7.3 that proceeded it or an '05 6.0. All of the diesels have a 100k powertrain warrantee unless they have been chipped. If you buy one under 100k, ascertain at a Ford dealer that the warrantee is valid before buying, it makes a large 4-figure difference in the value of the truck.
I'm selling my F-250 4x4 w/ a fresh 7.3 Powerstroke, if you are interested shoot me a PM. I want $11.5k for it.
