Jordan window channel balance

Hi,
The 29? long channel balances were stamped with 2820 or 2830. The 25? had 2420 and I guessed that the same height window with six panes that was missing its balances was 2430.
The sash guide I ordered matched the dimensions and screw holes of mine. The 18-064 is smaller than mine.

Thanks!

PS. Your expert forums are extremely helpful. You have a great site