Need L-shaped (not flush/flat) plastic storm window clips

I have a very large storm window pane (about 5' x 6') and need to replace several white plastic L-shaped clips on the exterior. The clips are held in by threaded bolts (not sheet metal or "tap" screws). There are no markings or numbers on the clips. I need a minimum of two to replace two broken clips, but would like to replace all 8 clips if possible. Thank you for your help!