Lucky for you the BMW mount for the GPS unit has a very popular bolt hole pattern that fits
many Garmin holders for various GPS units. The round plug carries power and the flat
tapered fitting is specific to the BMW Nav units.
I personally run a Garmin 376c unit (discontinued) but like it more than the current Nuvi units
since it is a marine / auto unit it is totally water proof, the display is bright and the quality of
the map image is far better than the Nuvi series. There is of course many draw backs to this
unit. These units do not compare with all the bells and whistles that the Nuvi's have.
Go to MAXBMW and look up your year and model bike for the parts listing and you will see a
cover for the black plastic, bolts and nuts that will complete the mount.
Below are picts of my 2009 LT with the same mount you have only with my 376c mounted!!
I don't use the flat tapered plug so I just tuck it away. This wiring is connected to the bike
and will turn off then the key is taken out - I believe!!