If your first large gear is black you have a VDO speedometer. The ONLY way to determine the correct tooth count needed for the E3 gear is to remove and count the teeth on your old gear. This is an amber colored gear, larger part will have 48 teeth, remove and count the teeth on the underside
E30 MotoMeter Speedometer
If your first large gear is orange you have a MotoMeter speedometer.