Noticed my diff was dripping fluid today. It looks like it's coming from the pinion seal. I did a search and came up with a lot of discussions of pinion seals. Sadly it seems to be a common problem. I know that I am not a good enough mechanic to do this myself.

From the posts and my Chilton book it looks like the crush collar and pinion nut should also be replaced. However should the pinion bearings be replaced also? Some people seemed to think that they should. From this diagram I see that there are front and rear pinion bearings. Should they both be replaced or is this not necessary?

 

The official way is to replace the crush sleeve and pinion nut and reset pinion bearing preload after replacing the pinion seal. This is because whenever you loosen the pinion nut, you've potentially changed the pinion bearing preload.

That said, I've replaced them before just by removing the nut, pulling the flange off, pop the old seal out, new one in, back together and away I go. Admittedly, I've been kinda hit and miss in this - axles aren't my thing. If done incorrectly, at best you'll get a little gear whine; at worst, the bearings will seize up, weld themselves to the pinion gear, and all hell breaks loose shortly thereafter. If you ain't sure about it, let someone else worry about it.