Caldwell winged block and tackle balance for side load single hung windows

Hello, thank you for posting, 

As long as the depth of the bottom shoe attachment is 1", the Series 380 should be a good match for you. For the 18" you will need a 1750 stamp option for a 20 pound window. For the 24", you could use either the 2360 stamp option that supports a 27-30 pound sash or the 2365 stamp that supports a 30-34 pound sash. Either stamp should work fine! 

For the top sash guide, please review the style and dimensions of the 18-171 to determine a good fit! Let us know what you think and if you have any additional questions.