[Brad54]

Agree with what others have said here--knock on the door, introduce yourself, tell him you were looking at the property on (street name) and got his name from the tax office, and that you'd like to talk to him about buying the truck to save it.
Be up front and honest. Don't low-ball him, and I wouldn't ask to buy just parts of it--nobody wants someone to part-out a vehicle on their property and leave the rest. Plus, he might think you're trying to scam him and say you just want to buy the bumpers, then steal whatever else you want off the truck.
Tell him you love these trucks, and would really like to buy that one from him.

Good luck!
-Brad