Mercury - Gen I Throttle and Shift Cable 18 Foot Mechanical Engine Control 8M0082491. The Mercury Gen I Throttle and Shift Cable (18 Foot) is designed for boats using traditional Mercury Gen I mechanical control systems. This cable connects the control box to the engine to provide direct, responsive throttle and shift movement without electronic involvement. The 18-foot length is ideal for wider hulls, deeper consoles, and longer helm-to-engine routing where additional reach is needed for a clea