Mercury - Harness Extension (Triple/Quad/5/6 Engine) 48-Inch Multi-Engine Extension 84-8M0158127. OverviewThis 48-inch extension gives you extra room to run trim wiring on larger multi-engine setups-triple, quad, and even 5- or 6-engine rigs. It includes the dash lead, the ERC pad lead, and the Y-harness, so everything plugs in cleanly without piecing parts together. If you're running Zero Effort controls or the bigger multi-engine dash trim pads, this extension helps the wiring fall into a smoo