We took the motor and first reduction gear out of the gear box, and made a custom gear box by putting a couple holes in two 1/8" aluiminum plates, and turned down a 3/8" hex shaft to fit into bearings, and allow a sprocket to connect to it. The plastic gears in the first two stages of the FP gearbox have 3/8" hex holes...they fit on the hex shaft...it works out pretty nice.
