Mercury - Triple Engine Instrument Adapter Shared Gauge Power Link 84-892323T08. Overview. Triple-engine boats need clean, predictable gauge behavior, and that starts with a stable power source. The Mercury 84-892323T08 Triple Engine Instrument Adapter keeps things simple by letting the SmartCraft gauges power up from any of the three key switches. No more uneven startups or gauges waking up out of sequence-this adapter ties the system together so the helm responds the same way every time.. Key