I just bought an 07 SCrew. Came loaded with the options I wanted but the radio is the base no frills factory unit, doesn't even have a CD player. My truck has the Sirius Antenna mounted on the passenger side roof and also has the MP3 direct line in, on top of the dash. Can I upgrade to the factory unit that has Sirius capabilities and the AUX button to play my ipod? Does anyone know of a model number? Thanks.