What do I need to mount the Garmin Overlander GPS to the 67 Designs JL Rail?

You will need a trackball, a carbon fiber arm and then an AMPS holder. You then attach the AMPS holder to the back of the Garmin 'puck' that attached magnetically to the Garmin Overlander GPS.

 

1 x https://www.67d.com/collections/series-20-rails-and-accessories/products/series-20-trackball

 

1 x arm from here and best is 'small' in either matte or polished: https://www.67d.com/collections/arms

 

1 x https://www.67d.com/collections/holders/products/amps-plate