Rust!

Wheel openings, spare tire wells, floors alongside driver (pull up carpet, padding, galvanized metal plate and look), jacking points, rear shock upper mount "clam shell" plates (view above rear tires, frame bracing under floors, door edges, all body seams, rocker panels near rear wheel openings, did I mention floors?

I could send pictures, but you'd need to send the children out of the room.

Also inspect the firewall and inner fenders, behind the hinges and under the battery tray and below the headlights fro inside the engine bay.

Also, check suspension and steering bushings. Good bet several are rotted, especially anti-roll bar ends.