After I had the tub sandblasted it blew away any seam sealant that was in the body joints. Now that I'm done pounding on the body and panels are now where they will stay I wanted to reseal all the seams.

I sanded every seam in the bed with 220 grit paper so the seal would have a good grip to the epoxy primer, blew it out with air, and applied a nice bead of Seam Seal. The Seam Seal stays slightly pliable and is completely paintable.