With only two touches you can quickly and accurately program your speedometer. Classic Instruments SN74 installs in-line between the transmission pulse signal or ECM speed output and your electronic speedometer. The SN74 converts all known pulse signals, including pulse sendors that replace mechanical speedo cables on early transmissions, factory VSS (vehicle speed sensor), and the computer (ECM) output signals to 16,000 ppm or 8,000 ppm signals. It also includes an additional 8,000 ppm output signal for your cruise control. Real-time calibration feature allows total fine tuning. The filtered power source eliminates interference. This compact module works with most all aftermarket electronic speedometers and the module can be mounted anywhere inside your vehicle.