Anyone know what this is, and do I need another one?

I am attempting to restore a 1973 Cuda. While replacing the rear quarters I notices a small bracket above left rear quarter glass bolted to the sheetmetal above the glass. There was not one on the right side. Anyone know what it is, what is it called? Do I need one on the right side? does anyone make them? Any help is greatly appreciated. See pictures. quarterglass.JPG quarterglass1.JPG
Author: Quiny