Disclosed is a differential transmission unit featuring active controlling of the moment distribution. The method includes receiving a command to generate a desired parity or data symbol using an XOR relationship between some of a plurality of parity and data symbols. At least one groove is provided in the housing cavity and a coil spring is disposed in a groove for making electrical contact with the ball and retaining the ball for rotation within the cavity with the stem at selected conical angles with respect to the housing centerline.