Mercury - SC1000 Speedometer 80 MPH SmartCraft Analog Gauge Black Face 85 mm 79-8M0135631. Overview. The Mercury SC1000 80 MPH Speedometer (79-8M0135631) gives you smooth, accurate speed readings with a bold, factory look. Featuring a black face, white numerals, and a glass lens, it fits a standard 85 mm (3-3/8 in.) gauge opening and ties directly into your SmartCraft system. It delivers real-time data you can count on - and supports SmartTow and other SmartCraft features depending on your engin