I bought my kit from eiskits.com. They will set you up w/all the necessary parts. BMW Assist is the factory emergency and concierge service that you can subscribe to. Your dealer can set it up for you if you want, but you might have to give up the option if you decide to install bluetooth. On early production '04s, you can only have one or the other.

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'06 X5 4.8is, TiAg/black, cold weather pkg., comfort seats
'07 750Li, TiAg/black, sport pkg.
'05 Ford F350 silver met./slate gray, Lariat, 6.0 PSD, CC, DRW, FX4