Window coil balance and pivot bar
Thanks for your post! The pivot bar you have here is the 26-336 Simonton Pivot Bar. If you only need to replace these, then this should be compatible with the existing shoe.
If you are looking to replace the entire balance assembly, you'll need to replace all of the hardware with the 15-259 Coil Balance Pivot Shoe, 26-083 Pivot Bar, 15-255 Coil Single Support and the Series 159 Coil Balance. The dimensions for the hardware can be viewed directly on the website.
Please see the video tutorials, tagged below this thread, for details on how to convert the assembly and for instructions on how to select the correct coil weight option.