This is the left headlight mounting plate for a 1970 GTO with the Endura bumper. These plates bolt to the back of the bumper and provide support for the headlight and trim.
This is used but reconditioned. The plate has been sandblasted, some minor damage was repaired with welding, primed with epoxy primer and painted. It would be excellent for a driver-quality car but maybe not for a show-quality car depending on how particular you are.
$50 plus $10 shipping to the 48 states.