Andersen Balance Search

I have Andersen windows from around 1982. The balances have these markings from the same window:
11600/2 (the other one is 11600/3),
US Pat. 3,335.455
Pat. 1967 Can

A local Andersen dealer said he needed the glass size to get me my information:
The visible glass measures 36-1/4" wide x 21-3/4" high.