Mercury - SC100 Data Harness 6-Inch SmartCraft Link Extension 84-880756T05. Overview. Short runs between SC100 Series gauges sometimes need just a little extra reach. The Mercury 84-880756T05 SC100 Data Harness adds six inches of clean, OEM-quality SmartCraft extension so linked gauges can be spaced naturally on the dash. It keeps the data line tidy, avoids strain on the main harness, and makes multi-gauge layouts much easier to align.. Key Features. 6-Inch Extension - Adds a small, practical am