70 Duster 5.7 Hemi/46RH

Unless I'm wrong, there is another 3 pin connector on the transmission itself (not overdrive tailhousing) for the OD and LU circuits. Middle pin is 12v, outer pins are GND for OD and LU. I'm guessing you mean that the PCM uses this output speed sensor to determine when to drive OD/LU solenoids, which makes sense, however how else would an early 90s 2WD vehicle with a 46RH get a speed reading? I didn't think they used tone rings on the rear axle at that point?

Regardless, if I can't get a speedo then I'll just use a GPS speedometer from Speedhut or something. I'm not entirely worried about it.