Same issues to look for as any GM pickup from the same years. Listen to the engine, they tended to have piston slap and burn oil. Intake gaskets leak, knock sensors in the valley under the intake fail, brake lines get rusty, rocker panels get rusty,wheel speed sensors had a TSB for corrosion, ABS can be a little finicky when the speed sensors start to do funny things.
Other than that they are a solid truck, basically a 1/2 pickup with a bigger cab and smaller bed. All the same issues you'd have with the truck and none of them are particularly difficult or expensive to fix if you are reasonably mechanically inclined. The only bad problem is the piston slap and it's really only a problem if the engine uses too much oil because of it.