Need the help with the parts

Thanks for posting. This is indeed a 15-177 Pivot Shoe, which uses Series 152 Coil Balances. However, the stamp on the housing doesn't necessarily indicate the spring weight required. For this particular balance series, it's safer to go with a stamp on the coil spring itself, usually near the tongue. If there is none or you are uncertain, I advise you weigh the window sash. Give me that exact weight and I'll be able to calculate the spring weights you need. 

If the window weighs 15.1 pounds, you can use two of the S152-8 8 pound springs, one for each side of the sash. This will equal 16 pounds of support overall--being within 1 pound of the exact sash weight works just fine. Let me know if you have further questions.