how do you repair the rear axle seal

unless you have worked on an axle assembly before, I wouldn't recommend tampering with this on your own.

first you will need to know the type of axle the 99 lincoln has.Integral,or removable carrier!These 2 types of axles require different maintaneance procedures.The seal is not too complicated to change out,but you need to understand the 2 different maint procedures,for the 2 types of axles used.If i knew what type it had i would tell you in this message!

I'm guessing this is the passenger's side rear axle seal. That side of the axle gets beat up more from recessed sewer grates, and generally road-edge bumps. Usually, what happens is that where the bearing rides on the axle, it wears a slight groove. I would get an axle shaft of a junkyard car (but from the driver's side, as they tend to last longer), and install it with a replacement axle bearing that is wider then the original bearing. This will spread out the weight a little more along the axle shaft, and hopefully not wear another groove. I had his happen on two cars, and this is how we fixed them.