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...
Had a 7.3. Have a 6.7 now but only because the truck was rusting out around the engine. The common issues with them have already been mentioned, thought they are minor really. Was always happy with the 7.3.
But this new 6.7 is a power monster, and so quiet and smooth. Hope it holds up like the 7.3 did. Had 176k on it when I sold it.