31235-ZZ3-003 Gear Case Assembly - Overview. The 31235-ZZ3-003 Gear Case Assembly is a crucial component within the Honda marine engine systems. This part houses and protects the gears that transmit power from the engine to the propeller, ensuring reliable mechanical motion and efficient power transfer in marine propulsion. Designed specifically for Honda outboard motors, this gear case assembly supports the lower unit system, helping maintain peak operational performance. Engineered to seamless