This black wire attaches to the Circuit Breaker coming off the starter solenoid on one end then passes through the firewall to mate with the top switch wiring harness at the other end. We believe that some 1969 harnesses may have used a fusible link wiring harness in place of this one. This harness and the circuit breaker can be used on those applications.
Ford part number C9ZB-15A669-B or C9ZZ-15A669-B.