I would check the shocks also, Check to see if the top bushing and nut is fully tight, I replaced my rod ends with moogs thinking they were bad and I still had knocking noise. The stock were completely shot any way.

 

So I got the truck back from the dealer and its still making the noise. They did in fact show me the old tie rod and it was worn pretty good. I'll take a look at the shocks next. I'm still thinking it may possibly be a ball joint. I had to pay $40 bucks for an alignment as well. They did a below par job with that. There is another dealer not too far away that I'm thinking about going to instead. I'd do it myself but hey its still under warranty.

 

Just did mine two weeks or so.
Replaced them with Moogs. They seem a far superior ball joint.
Just look how bad the OEM part was at the end of the vid.
http://www.youtube.com/watch?v=hor2hYxXvNk
Al