I recently changed the right front hub on my D2, and I also changed the axle oil seal since Rave says you should. Original symptoms were slight wetness on the knuckle, as well as 3 Amigos and the computer reported a bad sensor on that corner. It was pretty obvious the bearing and sensor had actually failed. I had trouble pressing the oil seal into place, seemed like it didn't want to go in, but I made a tool and did my best, thought it worked.

I haven't got a lot of miles on it since, but I started noticing wetness on the front knuckle again. It actually looked to be coming from the CV as that was the only other thing I saw wet. Seemed to only be on the outer (larger) folds of the boot. I assumed I damaged the boot while doing the work. But I can't see any damage. And after a few more miles, everything is really wet with what looks like diff oil.

So I'm assuming it's the oil seal. Either I didn't install it right. Or, it could also be, that I noticed a small wear ring on the axle shaft right where the seal lip rides. Is that normal?

I just went ahead and replaced the seal again. When I took it apart, it was obvious I didn't install it right the first time. I put the new one in, modified my tool to work better (I machined a ring to press in the seal and it's attached to a short pipe). That worked, and it went in pretty well. I was pretty confident it worked.

I drove the truck to work today, and it looks like it still leaking!

I can't figure out the cause, other than the possibility it's the wear rings I saw?

 

Check the axle breather to see if it is clogged, if it is clogged the pressure that builds up in the diff will escape out the weakest point.
The front seal on my rear diff leaked when I bought my truck, replaced my axle breather and it has not leaked since, that was 4 years ago.