Blacked out headlight extension?

ok, on every 1970 mustang that I have seen, the scoops in the headlight extension are blacked out. Mine however is not. So I am wondering if they are blacked out by painting it black or do I buy some black plastic that sticks to the scoop? Also did the 70 mustangs come stock with the scoop blacked out or did people do it to make them look different?

thanks for the help. I will look into several mustang parts dealers.