I am replacing my factory radio in my 2008 LTZ, and cannot see to locate the Factory XM receiver. Any one have any ideas where it is? I found the Stock AMP (in the trunk by the right rear tail light). Also can I use the same cables that pull out of the factory XM receiver and plug them directly into the Pioneer XM receiver that I just bought? I didn't see any connection on the back of the radio for an antenna or inputs. Any help, would be sweet! I am putting in a Pioneer GPS touch screen, and would give it up, if I had to do without XM.

The XM and OnStar systems share the same antenna.. and that's the black antenna on the top/centre/rear of the vehicle.