Mercury - SC1000 Speedometer 80 MPH SmartCraft Analog Gauge White Face 85 mm 79-8M0135627. Overview. The Mercury SC1000 80 MPH Speedometer (79-8M0135627) gives you accurate, dependable speed readings and the classic Mercury style. It fits a standard 85 mm (3-3/8 in.) dash hole and ties directly into your SmartCraft network for smooth, real-time data. The white face with crisp black markings and a glass lens keeps it easy to read in any light while matching the rest of your SC1000 gauge package..