Do you mean the Dixon-Bate 'Pinball Wizard'?
Andy had one for sale, don't know if he still has.
I take it that this is the one;
http://www.dixonbate.co.uk/html/universal_coupling.htmWithout knowing why you want it, it's the only universal coupling that's safe to use with a 'Hitch Replacement Stabiliser'
All the others have the ball as part of the pin & it's only held in place with a 'R-cliup' or over-centre clip.
Not a good idea on a bumpy road - all that's stopping the caravan/trailer from departing is a 4mm pin