Drop the driveshaft from the pinion yoke. This part is important for keeping the same pinion depth setting; on the pinion nut, make a line-up mark on it and the yoke, and count the number of threads that are showing on the pinion shaft. Then remove the nut, washer, and yoke. Pry the seal out with a hammer and screwdriver, or pry tool of your choice. Install new seal using a hammer and large diameter socket (if you have one) or a block of wood. Reinstall yoke, washer, and nut, putting the nut back to where it was based on the thread count and reference marks you made.

 

I just did this. The one thing I would suggest is changing the fluid and diff cover gasket at the same time. You will leak diff fluid when you change the Diff seal so it makes since to change it all.