Trying to match the 5/8 top sash guide & channel balance

Thanks for posting! The stamps on the balances are all the same. The different letters and numbers following the 34-5 are used by the manufacturer; they do not have any bearing on the type of balance you need.

That being said, to identify the correct replacement balance I will need to see a photo of the bottom attachment on the balance. Your photos only show the top. Please also include a photo of the spring side of the balance.

The top sash guide appears to be a match for the 18-166. You'll need to carefully compare the dimensions below to confirm that this is the right fit.

Detail of 18-166

Profile view of 18-166

Thanks for the additional photos. You'll need either the S378-35, S380-35, or the S385-35 to replace your balances. To determine the right replacement, you'll need to measure the shoe's depth.

You can most likely use the 3450 stamp option but be sure to double check that the sash weight falls between 30 to 34lbs.

Comparison of the S378, S380 and S385 balance shoes.