41112-ZY3-621 Vertical Shaft - Overview. The 41112-ZY3-621 Vertical Shaft is a critical component of Honda marine engine systems, specifically designed for the vertical drive system in outboard motors. This shaft transmits mechanical motion from the engine powerhead down through the lower unit to the propeller, enabling efficient boat propulsion. Manufactured to meet exact factory specifications, this genuine Honda part ensures seamless integration with existing parts, maintaining optimal perfor