[asolde]

I would say you are in the ball park at around 13k. Depends... there is a lot to look at. Where is the rust if any? whats the history on the truck? Has it been repainted? You need to look at every inch of the truck. Get underneath it and look hard at all the spots these trucks rust at. A truck that is 42 years old has had thousands of hands on it from good mechanics to bad mechanics. Best advice is to look at it in person if at all possible. Remember rust is like a iceberg a little on top and twice as much underneath.