First of all, make sure the check engine light comes on when you turn the key to run, position 3. This would detect the PO disabling the light. Of course, if the check engine light is lit with the engine running, you will want to take it somewhere that reads the codes for free, Autozone, Checker, etc.

The 5 speed automatic is about $5000 to replace new! No dipstick was factory installed so figure some way to suck out a little fluid for a visual inspection. The transfer cases were problematic in that the electric shift motor fails. Make sure 4WD works. You can only engage with the trans in neutral and the vehicle stationary. Engine speed will markedly increase in all gears with the 2.3 to 1 gear reduction

Make sure all the power door locks and power windows work. Test that all keys provided will start the engine (and keep it running)

If it has Arvin shocks (OEM), plan on replacing them, preferably with Bilsteins.
They will be dead! $750 +- 250

A recall on the catalytic converters may include this vehicle. They are having cracking problems so check exhaust for soot stains, etc. About $3000 a set!
recall would be free, welding would be much cheaper if you have to pay.

The fuel level gauge is prone to failure and will not display full when the tank is filled. Just a nuisance!

Still a great ride, my wife prefers ours to the Eldorado! Just get the best price you can.

Regards,

Jim in Phoenix