I have to say that THE BEST truck I have owned with exception to my current truck (2012 Sliverado 2500HD 6.0, 6 speed auto).
I bought a used 1990 F350 XLT crew cab 8'bed with the 7.3 and 5 speed manual. Bought from a friend that took it to Banks and had a large turbo installed, then added an overdrive unit witch made it a 10 speed if needed, limo sliding rear window and spring steel seats front and back!!
Truck was used to tow his sprint car trailer set up and crew.
I bought it with 250,000 on it and it ran strong, I added Chevron diesel additive and NEVER had any issues with that truck..
It ran strong albeit noisy, turbo gave that extra power it needed and it was good on fuel!!
I sold it when diesel fuel prices exceeded gas prices, couldn't justify driving a school bus sized vehicle back and forth to work. truck had 325,000 miles on it the day it drove away.. I see it around the area every so often so I know it is still going.
Bought a 2004 F150 SCREW 5.4, was a dependable truck but had to many pending issues,,it never let me down but spark plugs rear end and cam phasers were needing attention.. Bought the 2500HD and couldn't be happier now..
Good luck on your search,, If you find an older 7.3 I am sure you will be happy, there are a ton of upgrades for them and even after a rebuild will run for a long long time!!