OER Parts offers a wide selection of Body Panels for your 1976 GMC C15. OER Parts offers 1976 GMC C15 Full Firewall, 1976 GMC C15 Partial Firewall 1976 GMC C15 Firewall Body Mount Patch Panels, 1976 GMC C15 Firewall To Floor Braces, 1976 GMC C15 Firewall Extension, and 1976 GMC C15 Firewall Delete Plate.