back up lights wiring diagram

Hello
I,m getting ready to wire up my backup lights on a 1974 duster. Not original wiring harness. It,s a painless harness. I have the three prong switch on the transmission. It is a 727 trans. i purchased a wiring harness from the a bodies classifieds. It has 3 wires 2 side by side and 1 on top in a t configuration. I checked the trans switch and show condanuity
from the 2 outside post. Don,t think this is correct. Does anyone know if this is correct or do I have a bad switch.
Does anyone have a wiring diagram to wire the lights up? I put power to 1 wire to the backup lights and they work.
I really need a wiring diagram.


Thanks big block
three prong switch,the outside pins are for the backup lights, center pin neutral safety switch