This reference is taken from the installation instructions...
"The socket post of the Companion hitch is designed to
have two mounting options. In most truck models, the
gooseneck socket will be forward of the axle and the
companion socket post will install towards the cab of
the truck (position 1). If your socket is located over the
axle due to the frame configuration of your truck, as it
is in the 2013 RAM 3500 trucks, install your socket
post so the post is towards the rear of the truck.
(position 2), see figure B1."
Here's the link to the installation instructions...
http://www.turnoverball.com/sites/default/files/rvk3500_09_10_2013_0.pdf
It appears that depending where the socket is located relative to the rear axle centerline, you'd use position 1 or 2. The end result is that the hitch will be located over the axle.
Dave