1)NRX18 differential Gear/ball diff (I just put it on my M18)
2)NRX18 Bevel Gear also can fit into M18...(just need some modification on the center shaft)
3)I heard if want used after market foam tyre on NRX18...must change the M18 knuckle and the universal swing shaft together...(now NRX18 got come out inner wheel fit aftermarket tyre)
4)Motor mount
5)servo saver