Broke plastic piece behind license plate

[JCSC2]

Hello,

I was trying to install a license plate on the front of my car earlier(85 300SD) . Which I have done so several times. However this time I was pulling on it(to hard) in order to hold nut behind the plate to get the bolt to tighten up. This white plastic piece with a wing nut broke off. Now the bracket on is screwed into one side. I am confused on the design of this. One side is screwed in while the other has this white plastic thing holding it. Does anyone know what I am talking about or how to fix.

Thank you!

Joey

[P.C.]

I would post some pics clarifying the issue and ask a moderator to move this thread over to Diesel Discussion.