SIR-GM1 Compatibility

I was looking at getting a Directed Electronics SIR-GM1 Sirius tuner for my '05 GP, but I want to make sure that it is compatible. I have the base radio w/6 speakers. The description says "Compatible with 2003-2006 GM vehicles that operate on the GM Class-2 Bus (radio must have a BAND button or Direct XM selection to be compatible)".

I know that XM was an option, but does the base radio have the ability to display the satellite radio info? My GP didn't come with an XM tuner if that helps.

Sorry if this is a n00b question, but before getting my GP last week I had a POS '93 Thunderbird. Eventually I'll update my avatar. ;)

All help/suggestions are appreciated.

After I posted I thought that I may do some poking around. I found a compatibility matrix for the SIR-GM1.

http://www.directedsirius.com/Docs/SIRIUSConnect_SIR-GM1.pdf

So it seems I should be good to go. I guess what I need to know now is if GM prewired the '04-'07 base GPs for XM radio and if the base radio will display the satellite info. Also how do I remove the radio? I looked around but only found tips on removing a '97-'03 radio. Are the steps similar?

Anyone know where the XM module would be mounted on a 2005 GP, and if all GP's were pre-wired for XM?