Common things to check for.....
Leaking head gaskets: Although not prone to total and immediate failure
the most noticable indication is coolant leaking (get under and have a
look for signs of leaks)
Stuffed CV joints, ask if / when they were last replaced. When driving
make sure you dont hear any nast clicks when turning sharply at slow
speed. Check the CV boots (all 8 of them) for tears or cracks. If the
owner paid close attention to this then the CV joints don't fail very
often at all, failure is usually the result of a torn boot not being
replaced letting the grease out and the grit in.
Timing belts. Replace religiously every 75,000kms (although the listing
does mention recently replaced). Note they are a non-interference type
engine and breaking a belt will not destroy the engine.
Check for lifter rattles when first started from COLD.
Check it has clean oil in it, and has been changed regularly. (although
most ppl are smart enough to change the oil before letting someone inspect
it)
Noisy transmission: in all fairness accelerating in 1st in particular they
were never whisper quiet, but if it sounds excessively whiney then could
be in for problems at the kms.
Rust around the windscreen (also the value of electronic rust protection
is at least dubious)
Check sills, sump guard, exhaust etc. for signs of damage from being
bashed over rocks or the like
The wagon in the ad looks as though it's been looked after. I guess you've
had a look at a few and have seen that most are...um...well used

I sold
my '93 wagon a couple of years ago and got $5,000 for it, in excellent
mechanical condition, no rust etc. @ 190,000kms. There are (or were) a lot
of them on carpoint/carsales however advertised for ridiculous amounts.
Don't take it to mean they are in better condition.
Hope that helps
Regards
James