The speed sensor in my 1998 Durango is located in the rear differential. Yes, the speedometer signal comes through the ABS computer from the rear axle speed sensor.
The vehicle speed sensor is located in the transmission extension housing (rear of the transmission) on the left side. The wheel speed sensors will be located in the hub assemblies at each front wheel and in the rear axle for the rear wheels.
The output speed sensor for the tranny is located just rear of the transmission oil pan and offset to the driver's side a bit. You will loose a bit of fluid removing, so be ready for that. If you were meaning the Vehicle speed sensor, that is located on the rear axle.