Manual 4 speed, 350, and it probably has low miles, right? Not a whole lot to go wrong!
Bodywise, if the door bottoms are in tact and the cab corners are good, it should be a solid truck. The door pins did tend to wear out fairly easy on these trucks. The interiors were also prone to severe fading and cracking (cheap ass plastic) especially the dash, but it probably spent most of its life in a garage?
I'm assuming a dump box? Check for hydraulic leaks
81 4x4 1 ton....hmmmm, maybe $3,500? I'm not sure how to price one?