sstock has the right idea...
But if you are patient, you may be able to find one. You are in a better part of the country than here, that's for sure. The 3804's aren't nearly as common/easy to find used parts for as the 3100's. In fact, we caused a bit of a stir at Kansas City a few years ago when we had three of them on the show field together (Joe's, Mine and Jim Carter's). I can't say how hard it will be to find a complete box (only the tailgate, tailgate hinge stuff, and fenders are common with the other pickups. The bed sides, planks, strips, running boards and splash panels are unique to the one ton). You could be looking for a long time or one might pop up for you tomorrow as a result of this conversation, or who knows? Chances are, you will have a bit of a quest on your hands. Worth doing, though, if you have some time -- putting one together from new parts is going to be expensive (we like the Mar-K guys a lot and they have been good to all of us here at Stovebolt -- those 1-ton items are expensive to make and are a low-demand item, so they are rightfully going to cost more). And I'm not aware of anyone repopping the running boards and splash panels for us or the 3600 guys.
Some of the other guys should chime in who've actually had to replace their beds. I did not so I have no experience with sourcing/procuring any of the bed items.
