That is exactly what my vert looked like. It's lead as already mentioned. I heated with a torch and brushed it away with a wire brush so you don't get the lead airborne. Underneath that is about5-6 spot welded in the recessed quarter to deck seam. When I replaced my quarter, I welded that seam so it won't flex and will have the body man lay over it with either lead or lead free fill, or a suitable product. If you don't weld the seam what ever you replace it with, could eventually crack with body flexing. The picture attached is after I welded it and I did later grind it down a bit. The area is recessed so filling over it with lead or lead free solder will cover it completely.
