[Bigdav160]

It's hard to put a value on it without seeing the whole truck. Tailgate or rear doors?

I'd be surprised if that is the only rusty area. Check the lower front kickpanel area (top and bottom, below the taillights (under bumper). That shiny paint might be hiding other spots.

That spot behind the seat doesn't look as bad as mine. It appears someone ground away the top piece of metal to scrape out a the crusty stuff. What's it look like from the back side? There are a couple threads detailing the removal of the crossmember and replacing the bad area. The pic shows some of the floor is rusty. Take that repair into consideration.

That didn't make a whole lot of these rigs so selection is pretty limited and prices seem to be going up.