Cool!!! Got any pics of it??

 

We always called those doughnuts. Pretty much the gooseneck was just a pipe with a hole in it and you set it on this ball and put the pin through to keep the trailer from jumping off. The most common type around here looked like an upside down cup with a hole in them with no bearing they relied on the threads to turn. when you put them in the truck you didn't screw them all the way down.

 

Just incase you will be needing a hitch, this site is for you:
Largo, FL Trailer Hitch - 5th Wheel Hitch - Trailer Parts