Hello, I am restoring a 1972 Citroen DS Safari, their name for the estate version. A normal DS has a box section sill made of 1.5mm steel. To take the extra load carried in an estate, the box section has an additional 2mm steel plate on the outside. In the 70s, no attention was made to rustproofing, so water wicked up between the two layers of spot welded steel, merrily rusting away. I've cut away the 2mm steel and the 1.5mm steel. A local firm has pressed up the steel. The sections are just odd legged 90 degree angle, 8 inches by 3 inches. I will cut to the correct shape. Question. What can I do to prevent water from wicking up between the sheets and rotting it again? The 2mm will be plug welded to the 1.5mm. Plus plenty of seam sealer. Zinc weld through primer? Hot zinc spray both new parts of the sill with localised grinding to help the welding? The parts labelled 13 (2mm thick) were originally spot welded to 11 (1.5mm thick). And he must have been paid by the spot weld, there are dozens, some almost on top of each other.