These are notorious for leaf spring hangers goin bad. The front leaf spring brackets are normally fine (also a weak spot for these frames as that's where mine broke on my 96) but the back brackets and hangers normally fail/rust apart. Also check issues with the motor swap since you never know if someone did a half ass job. Rust is ALWAYS an issue no matter where you live but it is worse up north. Do you know what engine it has? The 4.0's had timing chain issues... If it has a bed liner try to pull it up to see if the bed is rotted out. Other than basic fluid checks (check level, color and check for leaks) I learned you can tell a lot about a vehicle by looking underneath it. If something looks skeptical then just use that against the seller to lower the price. Haggle because no one ever lists their rock bottom price.