This was a dealer installed option (during the '60's and '70's) on cars that did not legally have to run a state issued front license plate. I could sure use one....in very good condition, of course. Thanks for looking!!
Here's a nice one on eBay.
https://www.ebay.com/itm/NOS-GM-Cadillac-Oldsmobile-Buick-Front-License-Plate-Trim-Panel-Filler-1480301-/292115660032?hash=item4403733d00:g:DScAAOSwcaFZFp6j&vxp=mtr