Help, 72 duster NSS/Back up light harness hook up.

I am having the same issues. I have a different than stock wiring harness and I am trying to wire my back up lights. There are three wires coming off the NSS. One is brown with yellow, the other is black with a white stripe and finally the last one is all black. The brown with yellow goes to the starter relay and I can not figure out what to do with the other two wires.