Estate witter tow ball

[dghackett]

I have bought a 2011 Mondeo estate and it has what I think is a witter towbar and the 13 pin electrics. My problem is that it does not

have the detachable tow ball with the car (seller did not know of whereabouts).

Could someone who has a witter tow bar with detachable tow ball give me the part number for the tow ball so I can get the correct one hopefully 

from e bay or the like.

 

Thanks