Mercury - Gen I Throttle and Shift Cable 22 Foot Mechanical Engine Control. The Mercury Gen I Throttle and Shift Cable is built for boats using traditional Mercury mechanical control systems that require extended routing length. Designed for legacy Gen I control interfaces, it maintains a direct, hands-on connection between the control box and engine to keep throttle input and gear changes smooth, familiar, and predictable-especially helpful during docking, steady cruising, and everyday operatio