Do you already have the bit to slot the 'gooseneck' into? Or do you need the whole thing made?
Any decent metalworker can make you the bit for the end. I had the metalwork underneath made up on my old Paj by Icon Auto. Did a good job but were bloody expensive.
Right, I have a square tube type thing hanging out the back of the car, and we have a thingy that fits over a ball type thing on the trailer, So, I guess I need a thingy type thing to connect the two.