This spring pin is driven into a cross-drilled hole in a gearbox shaft to locate or retain an adjacent component, such as a gear, shift fork, or selector mechanism. It sits within the gearbox housing and functions as a positive mechanical stop or alignment dowel under shear loading. A worn or missing pin allows the retained component to shift axially, leading to gear clash or loss of drive engagement. The original pin is manufactured to the same diameter tolerance as the gearbox housing bore, ensuring a press-fit that does not loosen under vibration. On removal, inspect the bore for elongation; replace the pin only with one of matching diameter.