Window balances

A contractor from Baltimore MD says:
I have window balances that are stamped 37-9, these are 351 series. I need 20 of them for now, but you don't have them listed.
I also found another balance that has only the stamp 38. The window sash is 40 1/2" wide. These ones are 351 series as well, just don't know what option these would be. I will need 36 of these.
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Tom from SWISCO responded:
Thank you for posting. We should be able to help you out with these balances. However, I will need you to confirm a few things.

For the first balance (stamped 37-9), what is the length of the metal channel? Based on the stamp, it should be 38". I would like you to confirm this. If so, then check out our S351-38. As for the correct option, you will need to weigh your window sash, since we do not have a match for your stamp. Then, you can compare that weight to the chart of options listed under the S351-38 in order to find the best match!

As for the second balance (stamped 38), I would also like you to tell me the weight of the window sash and the length of the metal channel. It's an odd stamp; usually, a balance stamp has at least three numbers. It may be 39" long. If that is the case, then it will have to be custom made. I would like you to confirm first, though.
A quick learner from Baltimore says:
For the first balance (37-9), the length of the metal is 38" and the sash weights is 35.5 lbs.

As for the second balance (38) the length of the metal is 44" and the weight of the sash is 34.5 lbs.
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Tom from SWISCO responded:
Thank you. Looks like both balances will have to be custom made. Check out the Custom Order Forms I've started for you below based on your specifications and fill out the rest of the information. One of our representatives will get back to you with a price quote and an item to add to your cart.

1) S351-37 with a 3750 option

2) S351-44 with a 4350 option
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