1999 Ford F-150

Remove tail shaft from rear diff.
Undo pinion flange nut.
Slide off pinion.
With a seal removing tool or a large screw driver, pry out seal.
Clean housing wher seal sits.
Carefully knock in new seal, make sure it is square.
Inspect flange and if seal surface is grooved fit speedi sleeve or replace flange.
Fit flange and do up nut to torque specs,
Be carefull not to over tighten as diff may have a collapsible sleeve(pre loading for pinion bearing) and over tightening will damage bearings.
Replace tail shaft,
Check diff oil level.
Road test for noise.

Mark (mhpautos)