channel balancer possibly s395

Hey Alex. Since both fittings have wings, or those side tabs, I believe this is either an S380-18 or S385-18. If the shoe depth is greater than 1", it's a Series 385; but double-check to be certain. Use the illustration below as a reference. For a stamp option, go with 1730. let me know if you have further questions.

Comparison of the S380 and S385 balance shoes.

There is unfortunately no trick to it. You just have to measure it as carefully as you can and use your best judgment. If you have a pair of calipers, then now may be the time to break them out.

It should also be noted that your shoe may not match either dimension exactly. Being nylon, odds are they have worn down a little from constant use over the years, so figure that whatever you measure is going to be fractionally less than it was originally.