To find the correct amount, you should:
1. Consult your owner's manual: This is the most reliable source of information. It will specify the exact capacity for your particular Ranger.
2. Check a reliable online parts catalog: Websites like AutoZone, Advance Auto Parts, or RockAuto allow you to search by your vehicle's year, make, model, and engine to find the transmission fluid capacity.
3. Look at the transmission dipstick (if applicable): Automatic transmissions usually have a dipstick. However, relying solely on the dipstick for the *full* amount is risky; it's best to use the numbers from your owner's manual or parts catalog as a guide to accurately fill it. Manual transmissions typically don't have dipsticks.
Do not attempt to add transmission fluid without knowing the correct amount. Overfilling can damage the transmission.