Mercury - Dual Engine Mechanical J-Box Adapter Harness Racing CAN P Link 84-892323A10. Overview. High-performance rigs need wiring that keeps up with the way they're driven. The Mercury 84-892323A10 Dual Engine Mechanical J-Box Adapter Harness brings order and stability to racing setups that rely on mechanical controls. Built with an integrated CAN P link and diode protection, it ties two engines cleanly into the SmartCraft backbone through a racing 14-pin helm harness. The result is a tighter,