Mercury - Speedometer 80 MPH / KPH SmartCraft Analog Gauge Gray Face 85 mm 79-8M0065980. Overview. The Mercury Speedometer (79-8M0065980) delivers accurate, easy-to-read speed data in both miles per hour (MPH) and kilometers per hour (KPH). It features a clean gray face, bold white markings, and a clear glass lens that stays visible in bright sunlight or low-light conditions. Designed to fit a standard 85 mm (3-3/8") dash hole, this gauge ties directly into Mercury's SmartCraft system for real-t