I have two Milgard Sash window that need new channels replaced, both are the same size.
Bob from SWISCO responded:
July 30, 2019
Thanks for writing in. See either our S380-18 or S385-18. The only difference between these two balances is the 'depth' of the bottom nylon shoe. Compare both with your old hardware to see what matches best. You will need a stamp option of 1740.