New stereo, attaching to existing tuner behind glove box...
 

My 06 hummer has onstar/xm antenna and stuff installed, all works presently, im gonna install a kenwood head unit that is xm capable, thing is...can i hook up to my already installed xm tuner and leave everything alone, (sirius subscription, antenna, wires, and just hook up from new head unit(10 pin) to the old sirius tuner behind glove box? Or do i have to buy the sirius svg300 tuner thingy and call in and switch service and change antenna wires around and stuff?

First of all, I'm actually almost confused by this. A new member with a question makes their first post in the correct category???? :confused: :D This is a very rare event! Usually this would be on some random category or maybe as a reply to a thread from 12 years ago. lol

Anyways I'm pretty sure you will not be able to to use the factory tuner but.... you can find an antenna adapter to use the OEM antenna with the Kenwood XM tuner.

Follow up
 

Its because im a Canadian, im polite, thoughtful, and i can follow instructions, grade 1, page 2..

Good luck with it either way. For what its worth, on my 2003 the Onstar was the old analog one which is useless and can no longer be used. I also re-purposed the Onstar microphone and GPS antenna for my Kenwood DNX693S. Works great and no aftermarket antenna or mic anywhere. :) I do not have an XM subscription so I've never looked into that but I know there are antenna adapters so you can use the stock antenna with an aftermarket XM tuner. As far as I'm aware they will also transfer your subscription to another tuner but I have no idea if they charge anything to do that.

Cool, im just tryin to avoid buying that sirius svg tuner if i dont need it, ill get into my dash this week and ill take pics, im just waiting on another faceplate to pretty it up..