I Doubt you will get one from a main dealer anymore, I recently bought one from
www.justkampers.co.uk , not the cheapest part in the world but if you need one,,,,you need one simple as....
Plastic ones use an 'O' ring, metal ones tend to suit a proper gasket which isn't supplied with the ones JK send out. (so you will have to fabricate one).
Regards
Fritz,,,,,,,