I friend of mine has a 2003 F-250 with the 7.3L Diesel for sale that I am going to look at tomorrow. It has 75,000 miles on it, and I know it has had meticulous care (he is a retired heavy diesel mech...
I have a 2002 F250 with 7.3L diesel with 88,000 miles on it and pull a 10,500 lb fifth wheeler with no problems. The 7.3 is almost bullet proof, the Ford mechanics tell me it is the best engine Ford ever put in a pickup. Does not have the power and mpg of the 6.7L now on the market but one hell of an engine. :)