shaft separating from Diff
 

http://i58.tinypic.com/24gnjoj.jpg

I couldn't find anything relating to this, so I am sorry if it was somewhere, and I just couldn't find it.

The above picture is what I noticed while I was searching for a speed vibration. I have no idea which is the best way to tackle this, and want to make sure before I do something that ends up being more detrimental than actually fix it.

Can I just press the shaft that is coming out back into the diff? And then I assume I will have to go for an alignment.

like I said, sorry for a noob question, I just don't want to do more harm than good.

Unbolt the axle and pull the shaft coming out of the diff. Inspect for damage and replace the side seal. If there is no damage to the stub, reinstall it. It should "click" or "snap" into place.

Possible the c-clip inside has worn down, but it could just be a fluke that it did ...

And no you shouldn't assume you need an alignment