I have a GPS Ram Mount plate with ram mount ball made by Motorcycle Larry in the US.
This mount goes between the handle bars on St1300's, which is the perfect place to mount your GPS.
Comes with longer screws from mounting. Price $20.00
I also have a collection of assorted Ram Mounts and connecting pieces also for sale.
Please contact on 0432 208 147 if interested.
I can give descriptions of the mounts from the Johnny Appleseed web site.
You can get a look at the handle bar mount from the Motorcycle Larry web site.
Kind regards.
Tony. (youngSTer)