There you go! Glad you were able to get the cost down. Be sure you test drive it first!

Things I'd check...
If the engine has already been warmed up, let it simply idle for ~ 5 minutes then rev it and check for excessive smoke at the tail pipe. If you have it then you've mostly likely got a valve guide seals issue.

If the engine's cold, start it up and check for the same thing.

Does it go into and out of 4WD easily. If not, it's likely the vacuum system that locks the central axle disconnect. From 2WD at a stop, put it into 4wd and then take off. Do the 2 front wheels light up in your dash. They should.

From 4WD at a stop with the front wheel lock lights lit in the dash put the transfer case select lever into 2WD and then back up for 6-12ft. Did the 2 front wheels go out in your dash? They should. If they blink then that's something that needs to be checked. As I mentioned it's likely the vacuum system but you can use this to drop the price further.

Check the radiator expansion tank for any unusual residue. Check the radiator cap for the same.
Check the engine oil dipstick for level and unusual residue.
If either of the 3 above have a milky brown fluid it would be evidence of oil/coolant contamination which is common when the head gasket goes. If it has this, I'd ask when the gasket failed and when it was replaced.

Check the transmission fluid to see it's color. Normally it's a clear red fluid. If it's dirty it will be a dark brown/black fluid.

Of course check for leaks underneath both prior to & after your test drive.

Check for both AC cold air and Hot heated air.