I bought a 2.3L 5-speed ext. cab (97 model) about 3 years ago. It only had about 88K when I bought it. I'm up to about 115K now. Although it was otherwise very clean and didn't look to be abused, that truck had the nastiest cooling system I've ever seen. I flushed and flushed on that thing. Guess it had never been changed out.
A couple of other things I'd check/change:
- Change the transmission fluid (also looked like it was never changed) unless you're pretty sure it's been done recently.
- Check the slave cylinder inside the bell housing on a 5-speed. Mine was leaking, so I went ahead and had the clutch and slave cylinder replaced at 95K. I replaced the clutch master cyl. later; she still doesn't want to go into first gear sometimes, but that's another thread.
- Check the gear oil in the differential(s). Mine was down a good bit when I got around to checking it.