70 scamp rear bumper

I think maybe you have the wrong bumper. A '70 should have a light with a built-in socket and wire pigtail that has a round single wire connector. I don't think they started the "dash bulb" license lights until '73. Maybe yours is a '73 Scamp bumper?? Does your bumper have verticle jack slots? Do you have a photo you can post?
Thanks, Mark