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...
My dad has a 2000 F250 super cab short box 4wd with the 7.3 and 4 spd auto that he bought new many years ago. He's got around 125k on it now, and it's never given him any trouble. It's loud and not overly powerful by today's standards, but it's been a great truck for him. He's in his late 70s now and I'm pretty sure it'll be the last truck he ever owns.
I wish I had a little more confidence in the newer Ford diesels, because otherwise they do know how to produce a solid and reliable truck.