NSS / backup lights question

Cool, ya learned a little. Worst case of "not grounding" was years and years ago, "us guys" used to use landing lights. Local guy came in with old Ford pickup, had them installed in housings, mounted to front bumper. Bumper on those old Ford pickups were bolted directly to pickup frame!!!! Lights were grounding to bumper!!!!..........but bumper bolts were rusty and bumper was not grounding to frame!!!!

"He was a logger." "I'll just weld that SOB bumper to the frame!!!"