Nothing! I bought it for $800 and it hasn't given me any trouble. Nothing at all. Keep the fluids topped up, keep pouring petrol down it's throat (lots of petrol!), and it just keeps on going! I love it!!
Actually, the only problem I had was that the drivers seat lost a bolt and the runner sheared through. I bought a replacement seat which I installed myself for $60. 4 bolts to undo and do up again, et voila! That's the kind of maintenance I like.
Drinks petrol like it's going out of fashion, but with 225 section tyres, grips and handles great.
Totally comfortable, and has proved it's worth on more than a few long interstate trips.
Pretty fast up to about 80kmh, but then the 3-speed auto 'box just decides it's going to cruise after that. I've seen well-above legal speeds out of it.
Masses and masses of room - it's transported three people and three bicycles without using a roof rack. Enormous boot and interior.
Find a good one, and they will last you a life time. The one that I drive again is the 1984 ZK. Great engine, roomy, and in general just has great character. Cheap to maintain, and if you have it on LPG (like I do) it's fairly cheap to run.