Mercury - Gen I Throttle and Shift Cable 24 Foot Mechanical Engine Control 8M0085943. The Mercury Gen I Throttle and Shift Cable is designed for Mercury mechanical control systems that rely on a direct, hands-on connection from the helm to the engine. Built for legacy Gen I control interfaces, it helps keep throttle input and gear changes natural, smooth, and predictable-especially during docking, low-speed maneuvering, and steady cruising. The 24-foot (7.3 meter) length is well suited for boats