I bought my Rodeo new in 93 and now have 205,000 miles on stock engine and stock auto tranny. Although, the tranny acts up ocassionally, but it seems to have cured itself a couple of times. I only have to add about 1 quart between oil changes. My valve tick started around 80k, it seems to have gone away lately.

With any other used car - See if you can view the vehicle with the engine cold, that way you can open the radiator and check for the color and see if there is no garbage in there - you can't do this with the engine hot. Of course check the oil, belts, etc.. Ask when/if the timing belt has been changed. Test drive, and if you feel nervous pay $75 to have an mechanic give it a once over.

have a look here if you have the VIN, and see if it sync's up(this is a trooper page, but seems to match up pretty well with my Rodeo):
Trooper VIN

Compare: Edmunds and Kelly Blue Book to see if you are getting a good price for the truck.

Good luck.

-Robert