Andersen Corp Sash Balance

I need 2 balances. Both for same window. Number on the body is 11600A-3. There are numbers on the mounting flange:
519 153 7 89.
Both balances are numbered identical, both units are identical. Both have two springs; 1U, 1L each for each of the two sash cord pairs on resp sides.
The window is thermoglass and both U&L glass measure 24.75 x 16.25 inches.
Both need cleaning and my biryhday is the 4th of Feb.
Thanks for your help in advance. ..............Rich