Mercury - Gen I Throttle and Shift Cable 25 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 support smooth throttle input and predictable shifting-especially helpful for wider hulls and longer console-to-engine layouts where clean routi