Identification help on vinyl window sash balance

I am looking for eight replacement sash balances with channel dimensions of 9/16 W, 5/8 D, 29" L and a spring length of 13.25" (14" including the hooks). There is a stamp on one end marked "28 B, B.S.I.". The closest balance I can find is the series 350, the 19-002 looks fine but I am unsure on the shoe. The shoe i have is 1" L, 1" D, and withe the tabs 15/16 W. I am also unsure on the weight range of the balance but they do fit a 2'6" 5'0" vinyl window. Any help you could give me would be great and I appreciate the help section here on your site.

Ethan