Test the switch. Plain and simple. Put an ohmeter across the terminals.
See what it does. If it conducts while the trans is in reverse, then it is a reverse light switch.
If it conducts only in park or nuetral, then its a nuetral safety.
That will help you narrow down the wire question as well.
Hook an ohmeter to the solenoid energize wire on the starter , and probe the wires at the switch in question. If you have continuity on one wire, then you have the wire from a nuetral switch.The other wire will be from the key while in the cranking position. Simple logic...just think about it for a few minutes, and use an ohmeter.