Where is the Turbine Shaft Speed Sensor located on a 1998 Explorer?

The Turbine Shaft Speed Sensor (also sometimes called the Output Speed Sensor or Vehicle Speed Sensor) on a 1998 Ford Explorer is located on the rear differential. It's usually mounted on the differential housing itself, near the passenger side axle. You'll likely need to get under the vehicle to see it. It's a fairly small sensor.

However, a caveat: There's a chance it might be on the transmission depending on the specific transmission type in your Explorer. To be absolutely certain, you should consult a repair manual specific to your 1998 Explorer's year, model, and engine/transmission combination. A Chilton's or Haynes manual would be helpful. You can also look up diagrams online through parts sites like AutoZone, Advance Auto Parts, or others, by entering your vehicle's information.