Take a look at my thread. It hasn't been active for a while, but you should be able to find it (can't recall what the title is right now). I built a long box out of plywood, lined it with 4-mil plastic, then filled it with several gallons of EvapoRust from Harbor Freight. I laid a couple 1 x 1" stickers in the bottom to keep the bed off the bottom of the box, then laid the bed in upside down (bed rails down) and let it sit overnight. I think it did a pretty good job of de-rusting the bed. You could turn it over or lay it on its side to strip old paint off it. The EvapoRust will soften paint so that it can be easily remove with a wire brush (wear eye protection).
