I have been looking into using the BT30 MX spindle upgrade in a Series 3 machine. It comes with a VFD. The control board may need upgraded to run a newer version of PathPilot as well as the motor. It says in the installation instructions for the spindle upgrade that you need to have the servo upgrade as well. Does any one have any idea why this is? A better question is why hasn’t Tormach put a kit together for the Series 3? I would think that they would sell well.