2 channel balance looks like different numbers to me the window weighs 27.8 pounds

Hello there!

Thanks for reaching out to us. The 18-188 top sash guide comes to mind. Take a look at the specifications and see if they match what you need. 

Alternate view of 18-188

Alternate view of 18-188

We should be able to help with the balance. Can you show us a photo of the inside of the metal channel where the innerspring connects to the pulley mechanism? That'd be located in the middle of the channel.