I'm confused about compatibility of the bluetooth adapters that will work with my vehicle (and my phone). My dealer says that the only BT adapter that will work the my car is MB PN 67875874. When I searched for this PN it is a Motorola SLVR adapter. I see other BT adapters on Ebay MB PN 67875878 and this one is advertised as being compatible with early model E class vehicles with the command system installed and almost all BT capable phones. I have a Blackberry that is BT capable but need to know what adapter will work.