Mercury - Extension Harness 2-Pin Excitation and Ground 84-8M0176937. OverviewThis extension harness gives you a simple way to run excitation and ground to the isolator without stretching or patching together old wiring. It's a small part, but it makes the layout around the rig center cleaner and easier to work around. At five feet long, it gives you enough room to route it neatly instead of forcing tight bends. It's the kind of piece you appreciate when you're trying to keep the rigging bay fro