When i bought our MB the factory told me that the rear anti roll bar was from a Carlton estate and the anti roll bar rubbers are from the same.

The Vauxhall part no is VM 90065994 and being Vauxhall is stamped on the original rubber parts but is no longer available.

However the parts are available on e bay.Link below. They may need a slight slice with a scalpel .

http://www.ebay.co.uk/itm/FEBI-03885-Vauxhall-Carlton-2-6-90-94-EST-ANTI-ROLL-BAR-BUSH-FR-LH-RH-/190976046787?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item2c770f36c3

Many thanks to Dan for yet another great tip.