CSX chassis, painted body color. The original paint ones I have studied were primed gray (red primer for coachwork to be painted black) all over, painted body color all over, and installed.
On late cars it appears that chassis completed into running cars in California usually but probably not always, had the bright shiny chromium plated fixing screw heads painted body color before final installation of the deflectors. If Shelby American refinished a car all over, which was more common that most might imagine, or change body color then the screws heads were certainly painted over as that shop did minimal masking before repairs or refinishing.