[dsraven]

you could make the shackle into an H with a piece of stout flat bar welded in on it's flat just above the spring. then remove the center bolt and plug the holes with weld for added strength. if you do this off the truck make sure to leave some extra width and then use shims on each side of the spring and frame mount bushings in order to be able to remove the shackle easily. otherwise it could be pretty tight getting installed/removed