Channel Stamp

I'm looking at the stamp on my balance it does not say the full 4 numbers, it states "21 2" then after the "2" vertically it has 3 letter stamp "B.S.I.", then horizontally (same direction as "21 2" after the "B.S.I.") it's followed by a NG. I'm convinced the part I need is a 22" s380. Is there anyway to confirm the top and shoe attachment displayed in the S380-22 product picture is the exact replacement I'm looking for with my channel balance?

I'm almost certain that this is a series 380 with 19-005 top attachment and 15-005 shoe attachment, however would like an experts opinion.

Please let me know if there are additional information or pictures I can send to confirm.

Thank you,
Mark

Unfortunately the balance is still somewhat operable and if I take the sash out, I will have no way of putting it back together. I think I will "bite the bullet" and order a set and go from there. Thank you very much for all your assistance, it has been very informative.