What are some things to look for? How are the engines(5.2/5.9) in these trucks?

 

5.2 is really dependable the heads are weak and the trannys run hot any truck you buy off someone is probably going to have a weak tranny in it unless they have a cooler on it and had some work done on it the wiring in dodge trucks sucks. The plenum unless the upgraded modification has been done will probably have to be done.
All in all it's really not a bad truck just need some love and care to make it a nice truck the biggest + i have found is they are really easy to work on.
the frame i would say is 1 of the strongest out of Ford Chevy Dodge, body's rust rather easy unless cared for.
i have a 99 5.9 with a fisher plow on it i just did the tranny in its for sale im doing the plenum next weekend
if your in NY or close to NY i only want 3k for it.
its in very nice shape has 200k on it but almost no rust and runs very well

well there's my opinion. im sure there's lots more out there.
good luck on your Dodge if you get 1
http://utica.craigslist.org/cto/2511944988.html

 

most transmissions have been rebuilt by now, and if actually rebuilt, that's a plus, as its better than original. test drive it hard and get the trans hot and see how it shifts. if it hiccups one little time, be aware that most problems cannot be solved w/o a $1500 rebuild.

engine bottom ends are very durable, except the heads can crack and the plenum needs fix.
rear ends and front ends are ok.
rear end w/LSD is prone to break the clutch clips and stop being LSD's.
front ends can require some semi-expensive repairs to bearings, seals, u-joints, track bar. not overly complicated, but expensive if you pay someone else to do it.
mpg is low, 12ish city and maybe up to 15-16ish highway.

the trucks are tough, and the ride is stiff (as expected).