balance

Not so fast! First, let's agree on what that stamp even says. I see "33 3". What do you see? It'll determine what the length and option are.

If you'd like me to verify the Series, show me some photos of both ends of the balance.

If you don't want to go through that effort, you can see if it's the Series 385 this way: check if both the top and bottom attachments have folded "wings" pointing to the side, and measure the bottom attachment. Series 385 has wings on the top and bottom, and 1-3/32" in the shoe, as shown below.