If your rear quarter windows are loose, falling down or won't go up or down like they should then this may be your problem. This is a replacement plastic guide & rivet, it is a direct replacement for your broken part. It fits all 1971-1976 full size GM 2 door hardtop or convertible cars.
This plastic guide attaches to a metal bracket that is attached to the bottom of the rear quarter window (see picture), each rear quarter window takes 2 guides.
