Milgard Balancer 35"

Hello there. This looks like either the S380-35 or S385-35, depending on the shoe depth. See below. Your stamp of 3490 is from an older rating system we do not use. However that '19' should indicate the window sash weighs 19 pounds. In that case, choose stamp option 3430 (which denotes a balance that can support a sash in the weight range of 18 through 23 pounds).

Comparison of the S378, S380 and S385 balance shoes.