It looked like a metal credit card that was attached to the back of the owners manual. It was designed to assist the mechanic working on your car. Today it is one of the best ways to confirm what options came on your classic Chevrolet. However, it is done in codes. With this guide you can break these codes and document just how rare your 1965-1972 Chevrolet is.
Chevrolet Protect-o-Plate Decoder