1. Transmission-is it origional, is it rebuilt, any wierd noises.
2. Engine- miles, mpg, any wierd noises(excluding a slight lifter tick tick tick, which your bound to get with these engines.)
3. Rust-it looks like the truck used to be dark green but is painted black(maybe just the picture) if so, is there any rust hiding behind that paint(especially the rocker panels).
4. Lift-it says that it has both tuff country and skyjacker lift parts installed. Both are reputable brands(though the debate on that will never end) but keep in mind this is a fairly top heavy car.
That seems like a pretty dang good deal on that truck. Barring any engine/trany/major rust problems. It's only 300$ more than I paid for mine and it was stock. Those lift parts alone cost a grand.