2005 GMC Sierra roof piece question

[scarp2012]

Hello!

I just had a tree fall into my truck, and this piece fell off (among other things). I am having a very difficult time trying to find out what this piece is called and what it does. It left a hole in its place and needs to be replaced before any other damage occurs. I checked all of the forums and came up with nothing. Would anybody be able to tell me?

Thanks!

 

[mogleybear]

I believe that is the XM Radio antenna. The On Star antenna I think is over the drivers side seat position. At least it was on my 2003.