channel balance part identification

I would like to make sure I purchase the correct channel balance. The widow manufacturer is Kiro, in a Karsten mobile home installed in 2015. The channel balance is 27". There is no stamp but there is a printed code: 26-3 BK5 CMC 50. The part matches the picture for the 27" Series 385 Channel Balance. Does the 26-3 mean I should order the option 2630? The window measures approximately 281/2" by 34 1/4".