"Yes, I know a lot about these. There is a lot to look for. Main thing is rust. My Bed Rails that mount to the Frame are shot. Mechanically these Trucks are good.
Check the Ball Joints, they only last 80K, also was a recall on the CPS, I keep one in the Truck along W/ a 10mm socket and extension. Truck dies when it goes bad.
It must be the International 7.3 Liter if it is a Diesel, that was the best Engine. 97, 99, 00, 01, 02, and first part of 2003.
Depending on how it was used and how it was cared for they are good for 300,000 miles or more.
The Guy I bought the John Deere from traded his 99 in W/ something like 340,000 and still ran great.
arcarz.com has a 2002 full size W/ extended cab, 4wd 106,000 mi. for like $16,000.00"