What to check before buying used?

[npauli]

Here's another silly Newbie asking for buying advice:

1) What kinds of things would you want to check before buying to reduce your risks of getting into a nasty problem? For what I'm looking for (see sig), it sounds like injectors and clutch may be problematic, but I don't know the best way to evaluate the health of these components. I'm thinking visual checks, code reading, carfax, test driving, light wrenching, and mechanic's inspections are all viable options.
2) In hindsight, have you ever wished "If only I had thought to check ____ before buying, I might not have had this problem"?

[madmatt]

have you local dealer run the VIN to see what has been done to it at the dealerships in the past.

[Dakster]

Have you looked at extended warranties?

I've always been kind of up in the air about them... I have usually broken about even with them - however, I never like to gamble and it seemed like the safe way to go.

[Duramaster]

!!!!!! STAY AWAY !!!!!! from the six speed manual at all costs!!!!!! You loose towing capacity with the manual transmission and the flywheels are the weak link. The dual mass flywheel brakes easily and when it does it sets up a horrible vibration that is very severe at idle. I don't remember the cost of the flywheel, but it is not a cheap fix. The Allison is the best way to go. Ask around. You get a higher tow capacity with the Allison PLUS engine braking. :)

[Mark Rinker]

Get it on a hoist, look for leaks. The obvious ones are rear pinion, transmission, transfer case leaks (search on this topic), front diff. I have done all of these on my high mile 2002 - the front diff seal just started leaking at 250K...