Block & Tackle side-load (non tilt) window balance

We need more than measurements in this case. We will also need detailed photos of an undamaged version of the balance in question so that we can match up the design. Start by removing an undamaged version from the window and showing me a clear picture of the top end, bottom end, and stamp. 

Note that I may require more photos, but I have to know what to ask for, first.

Thanks for your photos. Based on what I see here, you have either our S380-26 or S385-26, depending on the depth of the bottom shoe. That's the only difference between them. I recommend measuring your shoe and referring to our dimensions to confirm the best match.

Comparison of the S378, S380 and S385 balance shoes.

Hello! Tom isn't here today but I can help. It looks like your stamp says 25 5 which means you'd want the 2550 spring strength option.