To be absolutely certain, you should:
* Check your owner's manual: This is the most reliable source for your specific vehicle.
* Consult a Ford repair manual: These manuals provide detailed specifications for various 8.8 differentials.
* Look for a sticker on the differential itself: Sometimes a sticker on the differential will indicate the capacity.
Don't rely solely on online information – always confirm with a trustworthy source specific to your vehicle's year and model. Using the wrong amount of fluid can damage your differential.