Mercury - Diesel Engine to Vessel Interface Panel Extension Harness 10 Foot Inboard Wiring Extension 84-879312T41. The Mercury Engine-to-Vessel Interface Panel (VIP) Extension Harness is designed for diesel inboard installations where additional distance is required between the engine and the vessel interface panel. It provides a factory-correct extension that preserves signal integrity without cutting, splicing, or modifying original wiring.. The 10-foot length supports flexible routing in larg