29" block and tackle window balance

I'm sure we can help, but that stamp only tells us the strength of the balance. Can you show me the attachments or fittings on either end? Those are needed to ID what you have. Thanks. 

Thanks for getting back to me. I believe this is an S380-29 Channel Balance. The Series 380 has a bottom nylon shoe with a depth of 1". The depth can be thought of as the 'heel-to-toe' measurement. Please measure to confirm this matches your balance's shoe. If your balance's shoe is closer to 7/8", you may need something else, so let me know. 

Your old stamp code of 28G might conform to our stamp option of 2870, which designates a balance that can support a window sash in the weight range of 39 through 42 pounds. Let me know if that seems right, or if you have any other questions. 

Thanks for getting back to me. It sounds like you have a balance with the 7/8" deep 15-029 Shoe attached. None of our stock balances have this shoe attached, but we can supply them to you via custom order. Note that (2) is our minimum quantity for custom balances. In that case, I sent you an email with a custom link to order a pair of 29" balances with the 19-005 Top and 15-029 Bottom fittings attached. These balances will be stamped 2870, which as I said early, means the balances can support a window sash in the weight range of 39 through 42 pounds. If you're uncertain that's right, I highly advise weighing the sash to confirm. Let me know if you have further questions.