2001 Screw, 189,000 5.4L 4x4 Lariat

I have oil leaking in front of the rear dif, and it is slung all over. I believe it is a pinion seal because a u-joint is going bad. I picked up two new u-joints and ordered a pinion seal tonight. I also picked up some 75-140 and limited slip additive. I looked up my codes and it looks like I have a 3.55 LS. I have 12 bolts on my dif so I am guessing 9.75.

My question is how exactly do I replace the pinion seal? Or what do I have to watch out for and mark up for re-installation? Thank you very much for any response.
Scott

 

That is a fairly involved answer. Do a search and you will see that most people will not have the tools to do the job properly. There are some ways to skip a few steps but you always take a chance on those. Have a read and see if you want to risk it.