Need diff help.

[mikajo39]

So today I drove my truck around for about 30 mins or so. Got home, and noticed where I normally parked fluid on the ground right where my diff would be. Not much so I only expected the cover to be leaking. So I park it, and my right rear is literally oozing gear oil out of the drum, and its sprayed about so it must have happened just a few moments before I got home (thank god). I'll take pictures soon, but any idea what it is that could have gone out? I had my wheel bearings and axle seals replaced about 2000 miles back when I had my brakes done. I'm a pretty competent mechanic, I just lack space and time to work on it, so if it is fixable in a garage I'll do it myself, if it's a bigger job, i'll take it in. Any words of wisdom would be great.