Non-tilt window balance replacement

Thanks for posting, and thanks for all the thorough information. So long as the bottom shoe is 1" deep, then I totally agree--the S351-34, stamped 3320, seems best. It does look 1" deep in your photo; but pictures of measuring tape can sometimes be deceiving, so do double and triple-check to be safe. The only alternative, as you may already have gathered, is the S390-34, which looks just like the Series 351 but has a shoe that is 1-1/8" deep instead. Otherwise, you should be good to go. Let me know if you have further questions!

Comparison of the S351 and S390 balance shoes.

You're very welcome! Best of luck on the rest of the project and please don't hesitate to reach out if we can be of any further assistance!