22G943-31 Teeth Idler Gear, with one shaft longer than other as per last Rover design. If the Mini drive train has a weak link, it\’s the connection between the engine and the transmission! The idler gear often takes the abuse caused by wear and/or poor assembly techniques. We see more of these go bad than we do any component in an engine! For the 4-synchro PRE A+ transmission. Shaft diameter is 0.750\”