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