Window spring balance

Hello,

We can't be sure with the hardware still installed but what I can make out reminds me of the 17/32" thick 15-199 pivot shoe and 26-378 pivot bar. I would recommend removing the hardware from the window to compare to the specifications below. If it's a match, the 15-199 is used with either the 1/2" wide Series 160 or 3/8" wide Series 165 coil springs. Take a look and see what you think. Thank you! 

Alternate view of 15-199

Alternate image for 26-378