V6 or V8?
If V8, timing belt might need to be done again (should have been done at about 90k and 180k).
If V6, maybe the timing chain needs to be inspected...? Not sure how long those are supposed to last.
Other than that, check the following:
-Brakes (seized caliper pistons are a common issue)
-Make sure it goes into 4lo without issue (have to put it in N for this, should not beep once in 4lo)
-Make sure the center diff lock works
-Make sure there are no leaks from the transfer case, diffs, where the axles enter the diffs, transmission, oil pan, etc.
-Check the coolant to make sure there is no oil in it (for the V6 at least)
Once you get it, I would put all new fluids in it, unless you have proof that this has been done recently (diffs, transfer case, coolant, ps, brakes, oil, maybe trans fluid too.)
Other than that, same as any car I guess. Make sure you test drive it (high speed and low speed). Looks like it comes with some sweet all-weather mats too. Enjoy!