Analysis of Leakage
WARNING: This page is about a different car, the 2019 Ford F-550 Super Duty, 2019 Ford F-450 Super Duty, 2019 Ford F-350 Super Duty, and 2019 Ford F-250 Super Duty. However, it is still accessible from the selected car via links, so may be relevant.
Clean up the leaking area enough to identify the exact source.
A plugged front axle housing vent can cause excessive pinion seal lip wear due to internal pressure buildup.
Verify the differential lubricant level is at the correct level. REFER to: Differential Fluid Level Check .