Got a little problem here. 64 Falcon with a close ratio T10 4speed. The speedometer do not work. New cable and gear. I can spin the cable from under the car and the speedo will register. Its definately not meshing woth the drive gear in the tranny. I can also see the drive gear moving if I turn the driveshaft. Is there different diameters of gears? They list the gears for 3speed and auto, or 4 speed. Im assuming the difference is the angle of the cut on the gear due to the oppisite side mounting. Any clues? There is no indication that the two gears have ever meshed. No sign of bad alignment or broken teeth.