Overland Models Milwaukee Road Steeple Cab

I recently purchased a Overland ES-2 Steeple cab, but it has an early tank drive mechanism in it. This is my second, the other has been repowered with a tower drive by the last owner I purchased it from. I don’t know who, if anyone makes a repowering kit anymore. Can anyone help me with this since I’d like to repower it if I can with a tower drive.