Window balancer
Hi there!
Thank you for reaching out to us. We can help with this. It will just have to be a custom order due to the 86 stamp. That tells me that your balance has a special calibration that isn't matched by any of our standard parts. Can you measure the bottom shoe and tell us the depth? How many balances are you looking to replace?
The part shown here is the top sash guide, which resembles the 18-178 pair. Take a look at the specifications and see if they match what you need.
The bottom shoe is at the bottom of the balance and is shown in the fourth photo of your original post. We'll need you to write out the depth to get the ball rolling. It should measure 1" or 1.088".