Gang...
Just finished installing the OEM Sirius tuner into my 2005 SLK350. Interesting thing on this. I'm not sure if it's just a Canada thing, but when I asked the dealer, they said it wasn't possible. They said they could do it on the 2006 and 2007, but not the 2005. As I got into it, I figured out why. While my 2005 had the power connecter (which is just +12, ground and MOST sense), it did not have the MOST fiber wire, or the pre-wire for the antennas.
That's not really a problem. I had no intention of installing the "wart" on the trunk, and like others put the antenna in the front vent, so didn't need the antenna wires anyway. And, you can order the MOST cable. Only other weird thing is I couldn't activate it online with Sirius. When I phoned them, they said they knew it was for a Mercedes. I couldn't figure out how to get the free time Mercedes gets (I ordered lifetime anyway), but did get free activation.
A note on the tuner, only get the second generation one listed below, not the dual lead antenna version.
Part numbers:
SDARS Tuner: B6 783 0060 (about $500)
SLK install Kit: B6 783 0078 (about $220)
Most Fiber cable (if required): A 171 540 74 09 (about $35)
Sirius Micro Car Antenna from Best Buy: SIR-CA1C (about $40)
Great install instructions from Bills Den:
http://www.billsden.org/fileadmin/me...ll_11_2005.pdf
Good Luck!
Dang