I tried and tried but couldn't get an XM receiver that was integrated into the factory navigation/radio. The car was equipped with a wiring harness (located behind the storage compartment between the seats) but I couldn't find the receiver. Cost estimates from stereo shops to the Cadillac dealership ranged from $300 to $500 but it always turned out that all they could do was install an XM modulator. So I purchased the Sirius Satellite Radio SIR-GM1 GM Class-2 Bus Compatible Satellite Radio Tuner. Total cost $62. on E-Bay and a $30 rebate from Sirius, net cost of $32.

The kit comes with a Mini-magnetic antenna that fits in the right front dash (the magnet sticks to the speaker cover), the wire can be tucked in the gap of the dash (above the air bag), behind the console of the radio, under the console where it meets the carpet, and into the area behind the console where the wiring harness is. I thought I might have to cut a hole to get it to the cavity but not so! Just push it between the panel behind the seat (where it meets to carpet) and it goes right into the cavity behind the console between the seats.

The rest is easy. Plug the Factory SDAR Interface Cable that comes with the kit into the Factory wiring harness, use some good double stick foam tape and attach the Sirius Tuner to the area where the factory XM tuner would be, plug in the antenna wire, and call Sirius to connect the service.

I heard you won't get good reception if you put the antenna on the dash, but that's not true (at least for the installation in my XLR) I would think it would be the same quality for all models, but I guess the quality might vary?

To sum it up --- no ugly antenna on my trunk, very reasonable cost, and great quality sound.

Steve,
Good information, now that's what this forum is all about.
BoboI tried and tried but couldn't get an XM receiver that was integrated into the factory navigation/radio. The car was equipped with a wiring harness (located behind the storage compartment between the seats) but I couldn't find the receiver. Cost estimates from stereo shops to the Cadillac dealership ranged from $300 to $500 but it always turned out that all they could do was install an XM modulator. So I purchased the Sirius Satellite Radio SIR-GM1 GM Class-2 Bus Compatible Satellite Radio Tuner. Total cost $62. on E-Bay and a $30 rebate from Sirius, net cost of $32.

The kit comes with a Mini-magnetic antenna that fits in the right front dash (the magnet sticks to the speaker cover), the wire can be tucked in the gap of the dash (above the air bag), behind the console of the radio, under the console where it meets the carpet, and into the area behind the console where the wiring harness is. I thought I might have to cut a hole to get it to the cavity but not so! Just push it between the panel behind the seat (where it meets to carpet) and it goes right into the cavity behind the console between the seats.

The rest is easy. Plug the Factory SDAR Interface Cable that comes with the kit into the Factory wiring harness, use some good double stick foam tape and attach the Sirius Tuner to the area where the factory XM tuner would be, plug in the antenna wire, and call Sirius to connect the service.

I heard you won't get good reception if you put the antenna on the dash, but that's not true (at least for the installation in my XLR) I would think it would be the same quality for all models, but I guess the quality might vary?

To sum it up --- no ugly antenna on my trunk, very reasonable cost, and great quality sound.

I had done the same about a year ago with the Sirius Connect Box but I have to say the audio level doesn't seem as loud as XM and both are very low compared to the CD and AM\FM.

Does anyone know if their is a gain adjust anywhere on the head unit or the bose amp?

BTW I own an 04 which is the older GM bus.

Had done the same last year with swapping out the XM tuner for the Sirius Connect box.

One thing I found is the HUD and Head unit would get out of sync if changing stations quickly - seems to be some timing issue with the 04 Class 2 buss.

Also now as of yesterday, XM has merged all the stations together so I have gone back to the original XM tuner because I feel the audio quality is better.

Also - I didn’t want to drill the trunk and add the factory bulky antenna so I purchased a Terk XMICRO2 antenna and Terk Single to Dual Antenna input splitter. (I have the older style XM tuner with two antenna connectors.)

The magnetic mount on the antenna sticks to the hinge of on the rear deck and seems to get good reception although I might route the antenna to the dash as noted on another post.

Also there is a big difference between the audio levels of XM or Sirius and AM\FM\CD. Does anyone know of a gain control for the AUX input on the Bose amp?

You may not have to worry about if the XM/Sirius stock doesnt climb above 25 cents a share.