Cell Phone Car Kit in 2003 GMC Sierra wit

I've heard that the wiring has changed for '03 in the Sierra/Silverado. Does anyone have this wiring info? (If the 2002 info is good then that will do).Is there a cell phone mute wire on this stereo?Can I use the existing OnStar antenna for the cell phone without dis-abling OnStar?Is it possible to tap into the OnStar audio with the cell phone kit?I hope someone can help me here, It's been hard finding info on such a new vehicle.Thanks Much!David

most of the wiring has changed although the basic ignition is still the same. you cannot tap into the antennaor audio  it is a dedicated circuit. the only thing you may be able to do is get an aux input harness and do it that way if the cell phone kit has the propper output. seems kinda expensive for a phone. there is a devise on tv i saw that just clips on the earpiece and broadcast on the fm like a cd changer maybe that would work for you without the expense.

Thanks Securinu,Actually this car kit has an amplified output. I was just hoping to use the existing antenna and speaker instead of duplicating what was already there for OnStar. What is this aux input harness? Are you talking about the OnStar interface for connecting aftermarket radios?BTW, for anybody with a Motorola V60 cell phone, I highly recommend Motorola's "professional install" car kit. The sound quality is excellent (sending and receiving) and the mute feature is nice.Dav

yes thats the harness for the radio.