What someone above wrote is accurate about no difference, but for springs, between the 250 and 350 in the 99-03 vintage.
Had I realized this when I purchased my F350 in 99 I would have gotten a 250 and saved a few bucks with yearly DMV registration weight surcharge.
Any 99 built after April 99 is known as a 99.5, which has a few improvements that were continued until the 7.3 was phased out. Also some differences in the front brakes/hub.
So you can likely expand your search to include 99.5 trucks and include F250s.
Good luck with your search.
Sent from my SAMSUNG-SM-G930A using Tapatalk