so, li'l background...
I am familiar with Sirius, and XM...or both(now)...

I have Sirius at HOME
I have XM in my Crown Vic P71-I installed a Pioneer/XM tuner-receiver and a Pioner CD head unit and it works very well since my head unit is "SAT-ready" so I bought the little receiver box to "translater" XM through the Pioneer....did the install myself.

Last weekend I traded in my '06 HHR 2LT that came with XM through the factory head unit...

I bought a 2005 Chevy Silverado 2500HD 2wd.

It has the stock head unit. I want to add XM to the factory sound system without replacing ANY part of the system.
it has the single CD player, and the Cassette, plus the BOSE speakers.

I have a Sirius little tuner...the kind you buy(sportster)...I dont want to 'add' it to my interior...I want to utilize the FACTORY head unit controls...screw the FM transmitter junk...reception blows...been there, done that.

I have read in the owner's manual of the Silverado that as long as my HU has a "BAND" button, I have a "SAT-ready" head unit...I can add it, and use the BAND button to scroll between FM1, FM2, and AM....and also XM.

anyone know FOR SURE which harness I need to buy to add to the port(s) on the back of my factory stereo?

does the BCM need a re-flash?

I dont have to have the 'GM harness'...there's a few "kits" out there.

Just hoping to hear from someone who has been there, done that and knows first hand.

thank you.

 

Try these folks, they have a fantastic tech department and they should be able to fix you up with info and parts.

http://www.crutchfield.com

 

I did this on a Trailblazer, but I am unsure of the wiring layout on the HHR For Xm. You would need to know if the wiring harness is still present even if XM is not ordered.

Parts I needed to order...

"T" Harness (Wires XM box to Radio Harness)
XM Receiver (Off eBay for $20.00)
XM Antenna (Used a Pioneer one, since I had to run it out of the truck, since the factory location required me to drill and It was not my truck)