34 4 AP CALDWELL

Thanks for posting. I believe this might be the S378-35 Channel Balance. The other possibility is the S380-35. The only difference between these two balances is the 'depth' of the bottom nylon shoe. See below. Measure your old balance's shoe depth to see what matches best. For a stamp option choose 3440.

Comparison of the S378, S380 and S385 balance shoes.

Glad I could help! Let us know if you need anything else.