Help needed,, p38 towball alko

Hello to all, i have a question regarding the towbar fitted to my 2000 model p38 and wondered if anyone could help me out?.
It's an al-ko towbar assembly thats fitted and i'm having trouble sourcing the towball to fit with this, the hole for the towball to fit into is a round one and has a pin on the lower part of the recess. can anyone shed light on this??
Many thanks phb

Alko-Kober used to be based in Leamington Spa, any caravan dealership should be able to give you their contact details as Alko also make caravan hitches. Maybe Alko also have a UK website which will list products and stockists.
:behindsofa: