Needing part number for the balance

Hello, thank you for posting,

Your balance assembly resembles the 15-087 pivot housing that is compatible with the Series 180 coil springs. Compare the dimensions to confirm a good fit! For a double assembly, you will need the 15-086 tandem housing. It appears that both housings are marked with the number 5. Take a look at the S180-5 coil spring. With (2) on each side, the total sash weight should weigh 20 pounds.

Detail of 15-087

Please review and let me know if you have any additional questions!