5th wheel to gooseneck adapter

[Scott & Dede Johnson <scottj@cyberlynk.com>]

This is slightly off topic, but I bet someone knows something about this.
We are looking at buying a 5th wheel trailer.  Both our trucks have
gooseneck balls.  A couple salesmen we talked with said there is an adapter
that can be bolted onto the trailer's 5th wheel hitch and then can be
connected to any gooseneck ball.  I'm trying to find a dealer that sells
these things.  The salesman at the lot where we want to buy said he can get
it for around $400, plus installation.  I'm guessing we could buy it cheaper
elsewhere but so far not luck on the net.  Any suggestions?  Also, if
someone knows more on how these things work, I'd love to hear about it.  We
have not yet seen one in person.  Thanks!

Dede
Central CA