These original 1956-1957 Chevrolet 4-door Hardtop left rear door window regulators have been fully restored. The door window regulators also fit a 1955-1956-1957 Buick, Pontiac & Oldsmobile. We replace any gears or nylon rollers that are broken or worn down. Often the springs are broken or the main rivet is loose causing the regulator to fail to raise the window all the way up. In this case, we install new springs or rivets so as to ensure that the regulator will work properly. When we get done with them they look and function like new.