Speed sensor

Left rear of the transmission tail housing.

It has a second one in the top of the differential housing that is used for vehicle speed on some vehicles.

Thanks Wrenchtech. That's for rear-wheel-ABS. It boggles me how that system works because the transmission sensor is not an input to the ABS system. It seems redundant because the speed of the two sensors has to always be the same. They're locked together by the drive shaft. My best guess is they want to insure the ABS system still works if the vehicle speed sensor fails.

The ABS system works by watching RATE of speed decrease of the combination of the two rear wheels. They could have done that with the vehicle speed sensor. I should have asked what the problem was; ABS or speedometer.

Yep, you caught me sleeping. I thought it was a Dakota for some reason.