Rc alloys I believe can make you a custom shaft. Contact
bill@rcalloys.com you will have to run cups on both sides and make sure you measure center of pin to center of pin. Make sure you tell about the small ball ends also. What size are the output shafts? and how long of a shaft do you need. If they are 5mm ,UE 5mm hardened cups would be perfect if they fit and you could use the big 8mm end shafts.