999U9-NV003 XM receiver
999U9-VQ011 mounting bracket
999U9-WQ000 factory antenna
You will spend around $400 for the factory parts if you buy through the dealer, maybe slightly less if you buy from an online vendor. The Terk micro antenna and a splitter are what most are using that have the factory receiver. It's alot smaller than the factory antenna and it can be run to the roof through the third brake light.
Crutchfield.com is a good place to buy the antenna and splitter.
I may be willing to sell my factory XM receiver, bracket, and Terk micro antenna with the splitter. I just need to decide if i'm going to switch to sirius first.
Hope this helps!
(Let me know if you are interested)