Me = 2004 Silverado (recently purchased - thrilled!)
My XM-SIRIUS reception is horrible. I read somewhere the satellite reception is off of a different antenna than the am/fm radio. Does anyone know of a satellite reception antenna built into the truck? Where? Upgradable?

 

Welcome from Florida. The XM-Sirius antenna is on the roof of the truck and looks like a shark fin. Check to make sure it is there and not damaged.

 

Ah, ha. Boy I should open my eyes... Regular antenna, plus two on top of cab: a boxy-fin one + one @2"-wrapped antenna too. I'm guessing one is SiriusXM and other is OnStar.

 

Not sure what you have but on my trucks the Onstar and Sirius use the same one.