Was backing out of driveway a few minutes ago. When I shifted from reverse to drive......load "pop" was heard and now it will not go forward in any gear......however, will go into gear and drive in reverse. Car has approx. 168k miles and has never had a problem with tranny slippage. Did the tranny go and will it need to be replaced....any thoughts on what happened and/or could it be something else? Any estimate on cost to repair in Tampa FL area. Should I take to dealership for repair or a Mercedes specialist? Thanks in advance!