If your speedometer is off or not reacting at all, the pulse sender could be an issue. It transmits the speed off the differential and sends it to the speedometer, so a severed cable or bad sensor could be the cause. Genuine part sourced from Porsche ag in Germany to ensure quality, reliability and precise fitment. Sold individually. 1 necessary per car.
"Speedometer Impulse Sender 911 85-86 / 930 85-88 - 915 / 930.36 Transmission"