Stamp on my window balance

A quick learner from 32817 says:
August 30, 2020
I have a house built in 1991. Of the 11 windows, 10 have bad balances or missing altogether by previous owner. I took one of the and the only stamp was "a 29-1". I can't find a match. I will need 10 pairs.
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Casey from SWISCO responded:
September 3, 2020

Hello,

We'd be happy to help but we will need to see a photo of the original balance removed from the window, including both top and bottom attachments, to compare to our replacement options. Thank you!
A quick learner from 32817 says:
September 4, 2020
Here are the photos you requested. There are some windows that are the same height but a bit wider. Does that make a difference?
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A quick learner from 32817 says:
September 7, 2020
I found out that the wider windows had the same style balance but the stamp was 29-3 a instead of 29-1.
Profile picture of Casey
Casey from SWISCO responded:
September 8, 2020

Hello,

Thank you for sending over the photos. Your balance looks like our S377-30 channel balance with a 2910 spring strength for the smaller window and 2930 for the larger ones. Take a look and see how our product specifications compare to yours. Thank you!
30" Series 377 Channel Balance
30" Series 377 Channel Balance
S377-30
$11.52
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