Anderson double hung from around 1989 - 11600-17 R27 89

I am looking for a replacement window sashe balance, the only markings I see on the unit are 11600-17 R27 89. I have not removed them yet, these are the only ones I can see with it in place.

Thanks for your help.

I pulled the other side of the sashe down and the other unit has11600-R2 939 R6 90 stamped on it.