Flat coil spring replacement

I believe you'll need the 15-180 Coil Balance Shoe to replace yours. To confirm, carefully look over the specifications below and compare them.

Alternate image for 15-180

This shoe is compatible with the  Series 190 Coil Balance, which is attached using the 33-073 screw. Your assemblies are anchored to the window track using the 15-186 Coil Balance Clip (single coil) and 15-181 Double Support Detent Clip (double coil), along with the 15-182 Balance Bushing. 

Take a look at the tutorial, tagged below this thread, for instructions on how to select the correct coil weight option.