The 489 has a crush sleeve so it's not as easy as just prying out the old seal and replace with new. The FSM has an elaborate procedure but there's an alternative.

Marking the pinion and the nut before removal is the easiest way. Use a center punch and make a dot on the end of the pinion threads and another dot next to it on the nut.

When reassembling, use a torque wrench set at 170 ft. lbs. to tighten the nut, if 170 is reached before the dots line up continue to tighten it until the dots line up; you will have the exact same preload as before you started. (I use some red Loctite as insurance)

If the nut is past the dots when 170 is reached the nut is too tight and the correct preload is lost. You can back the nut off if the dots are close but it's risky. (again, Loctite)