Mercury - Dual Engine Instrument Adapter Shared Gauge Power Link 84-892323T01. Overview. Running dual engines can complicate gauge power unless everything is tied together cleanly. The Mercury 84-892323T01 Dual Engine Instrument Adapter makes that simple by letting your SmartCraft gauges draw power from either key switch. It keeps the helm layout straightforward and removes the need for extra wiring tricks or isolated power feeds. Once installed, the gauges wake up reliably no matter which engin