Back up switch and harness

71 with 4 speed manual: A friend told me the other day that my reverse lights were not working. I finally got around to checking out why not and realized that I do not have a back up light switch. also there is no harness to go with it. I am hoping someone can give me an idea of where the wires would go to and how to get them hooked up once I have the switch in place. i do have the retainer fr the hurst shifter. Is it as simple as sliding the switch into the retainer? I can order the right switch from several sites, but what kind of harness do i need and does anyone know who sells them?

Thanks everyone, hoping I can get this put together so I can have the lights work eventually.

The NSS and backup lamps plug into a four-prong plug on the headlight harness. That's as much as I can tell you.

Check the car parts store for the switch. For the plug, maybe Don at OMS.