Determine What No. of Balancer Is Needed

Numbers that can be read. "11600-17" and "S88 7/02." "7/02" is likely to be when window was made. Do not have glass etchings but could supply them later.

Width of lower sash is (inside visible) 28 1/2", maybe 28 7/16"
Length is 27 3/4". Could be 27 15/16". W x L could mean window 2852 from what I looked at but Andersen Parts catalog shows differing Balancer depending on glass. Very confusing, hope you can help.