In retrospect I should have removed the bed completely and had it sand blasted. But unfortunatly, I have no way to transport the bed except on the frame of the truck. So I used 2 inch bristle discs to strip the ribs on the sides of the bed. Then I used a couple of wire brush cups on a grinder to strip the loose rust off the bed floor. Then I put 4-5 coats of Navel Jelly rust remover on the floor to get the deep down embeded rust off. That Navel Jelly really works, it has to sit for hours, not mins and takes a few coats but it cleaned up the bed floor fairly well.