channel balance with a hook

Can you confirm this is a 29" metal channel? If so, I believe you might need a S770-29 Channel Balance for a tilt window, but with a 62-105 Hook attached on bottom. This is not the standard configuration of this balance but we'd be happy to provide it for you via custom order. If you could confirm the length, and also tell me the exact weight of the window sash that these balances support, I can get this going for you. 

No, I'm afraid that's not what the last two numbers mean with this specific balance. The '40' designates a specific weight range, but because this is an older rating system we can't rely on it. Could you weigh the window sash, perhaps on a bathroom scale? Give us that exact weight and we can then work out what you need right away. 

I just sent you an email with a purchase link enclosed to order a pair of 29" Series 770 balances with the 62-105 hook attached. The balances will be stamped 29D, which means they can support a window sash in the weight range of 23 through 28 pounds. The hooks should attach to pivot shoes further down the window tracks. The pivot shoes are plastic blocks with cams from which the window can tilt inward. Let me know if you have further questions.