All early cars with L-76 or L-84 engines
The Over Rev. Warning System came as standard equipment on early 1963 Corvettes (and possibly other vehicles) with L-76 and L-84 (340-260 H.P.)
hi-performance engines, and a rare factory option on non-hi-performance 1963 Corvettes. To protect the engine from being over revved, this system would sound a buzzer when the engine's RPMs exceeded a predetermined factory setting. The system consisted of a separate wiring harness and a special tachometer that included a buzzer. This system was soon discontinued by GM when they realized that the buzzer was not audible at high vehicle speeds. The visual warning (red zone) on the tachometer would remain.
Electrical components such as a harness are non-returnable parts.
Always refer to a factory service manual when diagnosing engine service problems. You can damage electrical components if the proper procedures are not followed. Be sure you are replacing the correct part.