31246-ZY3-003 Gear Shaft Assembly - Overview. The 31246-ZY3-003 Gear Shaft Assembly is an essential OEM part within Honda marine engine systems, specifically designed to support the transmission system. Its primary role is to engage and transfer power from the engine to the propeller, ensuring the vessel operates reliably and efficiently. Manufactured to precise factory specifications, this assembly guarantees seamless integration with existing parts, maintaining optimal performance and durabili