My 12D 68 has them. Rectangular rubber flapper that covers the hole where the water drains out from the cowl panel. I believe ALL year Camaros have them....at least first & second Gen, never owned any newer than that! It was called Air Dry or flow through rocker system or something like that-designed to vent pressurized air from the cowl panel down through the rockers and out that hole there by drying out any moisture that has accumulated in them. If your rockers rotted out, it was because that hole was plugged.