Hello there!
I believe we can help with this. Can you flip the pivot shoe over and show us a photo of the front of it? Could you write out the width of the coil spring band as well?
You're also correct about the coil spring markings. The #4.0 represents the weight of each spring.
If your window doesn't have a cutout, see the video below and let us know if this helps.
I'm afraid this new photo doesn't show the pivot shoe. Our 15-199 came to mind when I saw your initial photo but this is just an educated guess. If our pivot shoe indeed matches up with yours, see the 3/8" wide S165-4 4-pound coil spring. The 15-205 is the compatible triple coil spring support. Take a look and let me know if you have any questions.
