T Built 12" Fifth Wheel to Gooseneck Adapter Hitch The T Built adapter hitch allows you to convert your 5th wheel into a gooesneck. Now you don't have to have the bed of your truck tied up with a large 5th wheel plate. Comes with the required hardware and has a total height of 13.5" or 11" from the top of the ball to the top of the mounting plate. 12" Tall Bolts right on to your 5th wheel plate. Keeps your bed available Uses a 2 5/16" ball