Need help identifying this balance

Thank you for you photos. To confirm the correct balance replacement, I'll need to see a photo of the bottom shoe. There are a few balances that have a winged top. A photo will help to narrow down the search.

It appears you have either the S380-35 or the S385-35 channel balance. To confirm exactly which one you have, you'll need to confirm the measurement for the depth of your bottom shoe.

Comparison of the S378, S380 and S385 balance shoes.

Also, we wouldn't be able to cross reference the stamp you have pictured, so you'll need to obtain the exact weight of your window. Once you've confirmed the balance series and the weight, you'll be able to use the chart located below the product description to determine which stamp option you'll need.