What do I order for 29 3 GO CALDWELL balance?

I am afraid that stamp code just refers to the calibration of the spring inside the balance, not the balance's identity. To help, can you remove the balance from the window and show us the nylon fittings at either end? Those fittings determine the type, or what we call Series, of balance you need. From there, we should be able to set you up with what you need. Thanks.

Perfect, that helps a ton. Take a look at our S380-30. Go over the dimensions, including the 1" shoe depth, to see if it matches what you need. You will need a stamp option of 2930.