Are you sure you have a "Turnover Ball" that is B&W compatible?
My used truck came with a Buyers Corp. Rotating Ball, that just tips up and is not compatible with B&W...
So I purchased the Star Performance Gooseneck Adapter in lieu of a standard Fiver Hitch as the Gooseneck ball was very robustly mounted and removing would have left a large hole in the truck bed.
http://www.sphitch.com