Need help identifying two sash balance replacement parts

A quick learner from charlotte, nc says:
Balance 1:
Markings - 2900 BSI KK
29 inches long

Balance 2
Markings - 3500 BSI JF
35 inches long

also including a photo of the brake for reference

Thanks!
User submitted photos of a window balance.
Profile picture of Paul
Paul from SWISCO responded:
Good afternoon. For the pivot shoe, check out our 15-129 and see how its dimensions compare to your own hardware. As for the balances, I think they look pretty similar to our Series 770 channel balance. What do you think? I'm not so sure what options you'd need, though. I recommend that you weigh your sashes and see what option on the S770-29 and S770-35 weight chart match them, respectively.
A quick learner from nc says:
Looks about right. I weighed the sash for both and placed my order.

thanks!
How to replace a tilt-window channel balance.
How to replace a tilt-window channel balance.
VIDEO
WATCH >
How to Remove a Pivot Shoe (Cutout Method)
How to Remove a Pivot Shoe (Cutout Method)
VIDEO
WATCH >
How to remove window pivot shoes
How to remove window pivot shoes
VIDEO
WATCH >
Anatomy of a tilt window
Anatomy of a tilt window
VIDEO
WATCH >
Reply to Thread
Use this form to ask a follow-up question or to share your experience regarding this subject.
(your email address will be kept private and is only used to inform you when a response has been made)
Current wait time is 3-4 business days
We promise that one of our experts will personally get back to you as soon as they are able. Thank you very much for your patience and understanding. If your inquiry is time-sensitive, please feel free to reach us at (888) 991-1929 or at help@swisco.com.