Mercury - Outer Helm Extension Harness 35-Foot Extension 84-8M0159755. OverviewThis 35-foot extension harness is built for wide-beam triple and quad engine boats where the outer engines sit a long way from the helm. When the standard harness won't reach cleanly-or the routing path winds around bulkheads-this extension keeps you from pulling the wiring tight or forcing awkward bends. It lets the harness run in a smoother, more natural line so everything feels calmer at the controls. On larger off