W124 Headlight Wiper Motor Shaft Lock

The purpose of this part is to lock the wiper motor assembly in place on the headlight housing, and to act as a torque arrester for the motor during operation. It's normally integrated into the wiper motor assembly, and is not available as a separate item at the dealership. They tend to break every single time one tries to remove the motor assembly - which admittedly should be rare. But if they do break, it's a couple hundred dollars for a new motor versus 20c in filament cost... No brainer.