correct channel balance
Do both of those attachments have wings, like the photos below? If so, you should measure the bottom shoe (the second photo) and see if it matches up. If it is the same size as the photo (1-3/32"), then you have an S385-20. If it measures 1", you have S380-20. If your attachments don't both have wings like the photo, let me know.
In any case, you must remove your sliding window sash (the glass pane and frame) and weigh it. The weight can be compared to the chart on the balance webpage to determine the "stamp option." Your "19-9" code is an older system and it doesn't match up to ours, so you will end up needing a different stamp.