License Plate Holder Lighting Question

[Gosman]

I have a 1975 argosy 26 and oredered a license plate replacement light . Question i have on the old license plate light i am going to take off my argosy has two wires a red and a gray ,
now the replacement only has one wire a red wire . I guess the red connects to the red wire ! Got that
but were does the gray wire go ???????? As i said the new light only has one wire and that is red .
Need help !!!!!!!!!!!!!!!!!!!!!
Thank you all george

[Soyboy]

I would think it is just a ground. Can you wrap it around on of the screws?