What else do I need with a 37 inch series 600 balance?

The 600 series balance can take any number of pivot shoes. If yours is an aluminum type tilt window it will could possibly take the #15-015 shoe. The vinyl type tilt window usually takes the 75-006. You use this tool to charge the spiral balance. You will need to charge your balance when you install the new replacement (roughly 3 rotations using this tool). This tool is also good to have handy in case you need to recharge any other older balances in your home.