What are the specs on the Ultimate Connection Rail version and the King Pin coupler that ships with it?

You can review the specs of the Ultimate 5th Wheel connection here and King Pin coupler here.

On a side note, for short bed trucks, you will need to install the base with the ball closest to the tailgate.
If you have an extra long pin box, the King Pin coupler block can be reversed to help with clearance issues (see manual or video on YouTube).