Mercury - SC1000 Tachometer 4000 RPM SmartCraft Analog Gauge White Face 85 mm 79-8M0135625. Overview. The Mercury SC1000 4000 RPM Tachometer (79-8M0135625) combines SmartCraft precision with classic analog styling. It fits a standard 85 mm (3-3/8 in.) dash opening and features a clean white face, black numerals, and a glass lens for sharp visibility in any light. This tachometer gives you smooth, accurate engine RPM readings while integrating SmartCraft functions like SmartTow and other advanced