Neutral safety switch harness question specific to 1974

RedFish said

yep , At one time the reverse lamp wires were inside the cab. The neutral safety wire didn't go into the cab. Just a single brown wire went from neutral safety switch to starter relay. When all this changed they routed the wires through previously unused ports of the bulkhead connector.
So that 3rd male connector is really a "wiper harness" connector. It was called that by some because it had nothing more in it. Neutral safety is brown. reverse lamp wires are purple/violet.
That's what you find in the dangly add on at bulkhead?

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Thanks, I saw a thread this morning posted by a friend that has a 75 schematic. It shows that configuration with the backup light circuit going into the cabin. In reality on my car, the brown from the nss also goes into the connector. Going to see if it has a mate on the inside maybe to an indicator light? Maybe it passes back out to the engine bay on another pin of the other two connectors?? Now I'm curious as to why they did it.
For my purposes I think I'll make a nss harness and use the two leads into the cab for the backup circuit and run a new brown lead direct to the starter relay. Thanks for your help!