Part

Thanks for posting. Do both nylon attachments have 'wings' or side tabs? The top one clearly does, but it's tough to see the bottom one in the photos. If it does, then you have either an S378-30, S380-30, or S385-30. The only difference between these three balances is the 'depth' of the bottom nylon shoe. See below. Measure your old balance's shoe depth to see what matches best. In any case, for a stamp option choose 2940.

Comparison of the S378, S380 and S385 balance shoes.