Window balance

Thanks for posting. Does the top fitting resemble the 19-005? If so, this might be an S380-29 Channel Balance. The Series 380 has a shoe that is 1" deep; however, so long as you're certain your old balance's shoe is greater than 7/8" deep (or 14/16"!), then I think this is just a Series 380 where the shoe wore slightly from age. You can always check another balance, either the other from this window or from an identical window in the house, to be safe. Let me know what you find. For a stamp option, choose 2840.

Comparison of the S378, S380 and S385 balance shoes.

I think it'll be okay. I agree that the design is a little different, but not in a way that matters. It's just a superficial difference as a result of your balance being an older design, and likely made by a different manufacturer. The function is identical. 

Yes, a stamp of 28D usually matches our 2840 option. These are traditionally organized in sequential order, so A=10, B=20, C=30, and D=40. Hopefully that makes sense. As long as your sash weight falls in the stated range of 23 through 28 lbs, it should work just fine.