$500-$2500. But if it's an F150, I doubt it would have a diesel in it, they didn't come with them from the factory in the half ton, and I can't think of any 6cyl diesel that wouldn't cave the front suspension in on one. They ar enot worth a lot of money regardless, but if it has a gas 6 cyl that had to be rebuilt, I would proabably move on since it's pretty darn hard to wear out a 300CID Ford 6.