To find the correct amount:
1. Check your owner's manual: This is the best source. It will specify the correct type and quantity for your specific transmission.
2. Look on a sticker on the transmission: Sometimes there's a sticker on the transmission case itself indicating the capacity.
3. Consult a repair manual: A Haynes or Chilton repair manual for your specific year and model Ranger will list the correct fluid capacity for your transmission.
4. Contact a Ford dealership or parts store: Provide them with your VIN number. They can look up the correct information for your truck.
Do not attempt to guess the amount. Overfilling can damage the transmission. It's best to get the precise amount from one of the reliable sources listed above.