First you need the special wrench to remove the large nut........then you need the determine what bearing arrangement you have, (with spacer or not between the bearings).
With spacer is just re-torque when reassembled and your done, No spacer requires a rolling torque of less than 6-8 inch lbs and locktite on the threads of the nut that you are torquing.......
The seal is about $30.00 +/-........
it gets pressed out of a aluminum carrier and the new one gets pressed in, pay attention to the way the seal lips are facing!!
Also if the yoke is worn (grove from seal lip) you may need to press the seal back into the carrier a bit further to have the seal lips make contact with new metal surface on the yoke. (a little trick to avoid replacing the yoke assembly) Just make sure you do this in the correct direction and only about 1/32 to 1/16" !!
the direction to over/under press the new seal into the carrier should be understood before doing it.
I would have to be looking at one to tell you specifically and I am not near one right now.
If you don't have a manual don't try it...........