As far as the motor they are as solid as they get...automatic transmissions are prone to failure though so I would reccomend a stick.
The only other thing I can think of is a mild fuel starvation on the 7th cylinder (I think) that can be cured with a simple and cheap crossover kit to balance the fuel pressure in the rails...if not its like 20 bucks in parts you can put together in your garage and find at a hydraulic hose shop, its known as the "cackle" which really isn't an issue but most do it as prevention.

Get a programmer if it doesn't have one already, in stock settings they are a bit of a dog but a programmer turned a stage above stock makes a big difference all around.

Get rid of the cat and muffler, they are useless and you don't smog a diesel anyways.

2wds eat ball joints a bit but they aren't hard to replace as its a single unit with the rotors.

Ummm...that's all I can think of off the top of my head really. If you are looking at an auto I would offer less than a comparable stick unless it has been rebuilt recently but even then I would shop around to swap a manual into it (it is what I am currently doing to mine due to failed auto).