Window balance need identifying

Hi there. This looks like a S770-35 Channel Balance and 15-129 Pivot Shoe. Make sure your balance attaches to the top of the window jamb with a screw; if it uses something else like a hook, please show me. To know what stamp option to select, obtain the exact weight of the window sash. You can then match that exact weight with one of the weight ranges listed alongside each stamp option on the balance's shop page.