I need balance coil

Thanks for reaching out to us. It's tough to say exactly what you have without seeing the front of the pivot shoe, but based on what I can see I think you might want our S140-11 coil balance assembly. Two of these can carry sashes weighing 21 through 22.99 pounds.

As for the pivot bar, I would suggest either the 26-405 or 26-398, depending on hole placement relative to the front tip. Review their dimensions to determine the better option.

The S140-11 carries 11 pounds per assembly, not per coil. 

As for the 5L and 5R stamps, those typically indicate 5 pounds, yes. That would add up to 10 pounds per assembly, which is close to your stated sash weight of 21 pounds.

At the end of the day, stamps vary from manufacturer to manufacturer and era to era, but the hard numbers never lie. If your sash is 21 pounds exactly, then focus on that.

My recommendation is for the S140-11. As stated previously, a pair of these carry an overall weight range of 21 through 22.99 pounds.

The S150-05 would be too weak, since a pair of these only covers only 9 through 10.99 pounds.

You can see how much weight each product holds on their respective store pages.