Upon further review (not listed and a little tough to see in the picture), it appears that the Trailer Towing Module might come in the Trailer Hitch Kit (Part No. 71602156525)??

__________________
E60 M5
E31 850i
E70 X5 xDrive35i Premium
E60 535i xDrive
E36/7 Z3 2.8
E46 325Ci