AOD Neutral Safety Switch Wiring

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I'm installing a 302/AOD combo from a '83 van in my '54 Ranch Wagon. I have the factory plug from the van harness. I believe the NSS is just a pass through switch that when the trans is in neutral or park the power coming in from the ignition switch is passed onto to the starter solenoid. Both of the wires on the plug for the NSS are the same color - pink with black and there location jives with the diagram I've attached. The other 2 wires are for the back up lights. One is black and the other purple. One should be 12 volts coming in and the other 12 volts out when the trans is in neutral but I don't know which is incoming hot and which is out going hot to the lights. I can barely see the switch on the trans so I really can't get a test meter to it to sort things out. Can anyone tell me which wire should be hot coming in? or do I have this all wrong. If so please enlighten me. Thanks in advance.