Obviously you will need the new seal.
I couldn't loosen the nut on my own a couple of years ago, so I took it to a shop so they could use an impact gun on it to remove it.
I was going to replace it myself, and did it by removing the driveshaft, then with a centre punch and hammer, I marked the position of the nut on the pinion so I could realign them afterwards and tighten it slightly more during reassembly so as to not preload the bearings too much afterwards, but also to not underload them as well. As I mentioned, I couldn't perform the work myself because I don't have air tools so I took it to the shop and explained to the mechanic what I was going to do to replace the seal. He followed my instruction and replaced it. When I got home I pulled the driveshaft off to make sure he tightened the nut properly and he did. It has been two years since I had it done and no leaks or problems with the bearings.
Hope this helps,
Hoppy
