2005 SL ... adding Sirius
Do I simply add a receiver and I'm all set to activate (Mercedes-Benz part#169-827-0162 or such)?
Dealership will want around $1200.00 for everything.
RBrenton (Now Mister Brenton I believe) can get you hooked up on the parts for much less.

gen 2 or higher antenna.. as for install its not for a diy but its not that difficult you will have to take the whole rear interior apart and a hole needs to be drilled in the trunk for the antenna so make sure you get a good installer



