Product Code: S795-35. I will include pictures.
Although the balances I need to replace have a 35B stamp, I think I should bump up to a 35C since the sash weighs 23 pounds.
FWIW, there are two sashes in the window. Although I have not removed it to confirm, one sash has a single working balance that I assume is also a 35B. Since that window works, I did not want to risk breaking it to confirm.
Thank you.