They must have changed between 68 and 69 as all my 69's have used the z for the reverse lamp.My 68 "Z" port was already utilized for the front left blinker per the wiring diagram. Basically you can use any two empty ports on the bulkhead side by side in a pinch. The wiring in the car should be a purple and white wire in the harness that need to mate with the wires from the reverse switch in the trans harness. Once the trans goes into reverse, that circuit is completed and the lights will go on. Just did both my 68's last year after years without reverse lights. Pretty simple once you do one and see how it works.
