A sample from the products for the Transmission (model M/n/p/r/s E2,e4,e17,e21,e24,e34) include: Bearing(20x52x15), Bush,4th Drive Gear, Circlip, Gear,third Driven.
On this parts fiche the Washer,lock is the most specified component.
The lowest price component in this Transmission (model M/n/p/r/s E2,e4,e17,e21,e24,e34) parts-list fiche is the Circlip.