Double hung window channel balance part identification

Thanks for your post! Your balance can be replaced with either the Series 351 or Series 390 Channel Balance. To determine which series is the correct match, you'll need to confirm the depth of the shoe.

Comparison of the S351 and S390 balance shoes.

In regard to the balance length, does this 17-7/8" length include the top and bottom attachments? If so, I'll need to know how long the metal channel is, without them. Please also confirm the stamp/marking from the metal channel.

Don't hesitate to reach out with any questions!