50531-ZV7-000 Reverse Lock Shaft - Overview. The 50531-ZV7-000 Reverse Lock Shaft is a vital OEM part designed specifically for Honda marine engine systems. This shaft is integral to the reverse lock mechanism within the transmission system, playing a crucial role in engaging and securing the reverse gear. By physically locking the reverse gear mechanism, it ensures stable and reliable reverse propulsion for boats. Manufactured to Honda's precise factory specifications, the shaft guarantees seam