Channel Balance Help

Is the metal channel 15" long? If so, I believe this is an S770-15 with a stamp option of 15B. There seems to be a rivet attached at the top of the balance so that it can attach to the window jamb using an S-Clip like the 19-029 or 19-030, sold separately. Our standard Series 770 attaches with a screw instead, but we'd be happy to custom build balances with a rivet installed on top to use the s-clips. Can you confirm for me that the rivet the s-clips use on your old balance is in the top hole of the metal channel, and not the second-to-top hole? Also, how many balances do you need? From there we'll get this moving for you.