To find it, you'll likely need to:
1. Consult a repair manual: A Chilton's or Haynes manual specific to your 1999 Chrysler Town & Country will have diagrams showing the exact location of the output speed sensor. This is the best approach.
2. Use a online parts diagram: Many online auto parts stores (like AutoZone, Advance Auto Parts, etc.) allow you to select your vehicle's year, make, and model and view diagrams of the transmission. This can help you visually locate the sensor.
3. Visually inspect the transmission: Carefully examine the transmission case for a sensor that is roughly cylindrical in shape with a wiring harness connected to it. Be cautious as you'll be working around moving parts.
Important Note: Before attempting to locate or replace the sensor, be sure to disconnect the negative battery cable to prevent accidental shorts or damage. If you are not comfortable working on your vehicle's transmission, it's best to take it to a qualified mechanic.