I have a roll of the Chevy Duty fender welting (as they call it) My truck had flat welting like you describe. The Chevy Duty stuff has a 3/16" bead that sits down flush on the joint. That's good because the bead covers any uneven areas in the joint and looks much neater. I was just wondering if anyone had gone beyond that and tried to seal the joint between the metal>welting<metal joint.