Need to replace this balance; I would like to do both sides

With this combination of attachments, you could have either an S380-27 or S385-27 channel balance. You’ll need to measure as shown below. The Series 380 has a 1" bottom attachment, and the Series 385 has a 1-3/32" attachment. You'll also need 2640 spring strength options for your replacement balances.

Thank you and let us know if you have any other questions or concerns.

Comparison of the S378, S380 and S385 balance shoes.

It sounds like you'll need the S385-27 channel balance with a 2640 spring strength option. Thanks for posting!