rust, rust, rust, rust and err, did I mention rust!
sills, body mounts, chassis, tailgate. pretty much anywhere really. As a result of that, look out for filler and poor quality repairs.
if it's a 5 speed drive it in all gears including 5th. 5th is an add on and quite weak, doesn't like going for a long way at speed when it's hot. If it's noisy a gearbox rebuild could be on the cards for the future.
If it's got the later push button 4wd select make sure it engages. Leaks in the system can develop