need 2 window balances.

Thanks for posting. See the S380-35 or S385-35 Channel Balance. 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. You have to choose a stamp option, which reflects the strength of the balance. Your old balance's stamp of 34-9 is from a rating system we do not use. If the sash weighs exactly 34 pounds and not over, you can choose a stamp option of 3450, which denotes a balance that can support a sash in the weight range of 30 through 34 pounds.

Comparison of the S378, S380 and S385 balance shoes.

Hey there. If the sash weighed 34 pounds or slightly over 34 pounds, the 3460 stamp will work fine. There's some overlap with it and the 3450 stamp. And if the shoe was 1" deep, then the S351-35 was the right choice for a balance. Let me know if you have further questions.