The metal "flap" that runs along the interior rocker doesn't support the sill plate. Only provides a protected wire chase for the body harness and any other (conv top, defogger) sub-harness routed from driver footwell rearward. If you are missing it don't worry. I like a non-conducting material anyway. I've used UHMW plastic sheet 20 mil or heavier taped in place with gaffers tape. UHMW is very tough and translucent too. It comes in roll widths and cut sheets. Carpet comes up under the sill plate too and everything is retained tight to the rocker once the sill plate is secured.