I really do appreciate your assistance with this - thank you.
Unfortunately in that diagram it is not shown as a separate item/part (In effect its just a top mount for the shock) - but although it does mechanically come off the strut easily (single nut) it is not shown as a separate item.
in that diagram the 'pin' in the centre of the top three mounting bolts is an externally threaded tube coming out of the air suspension unit. releasing this nut releases the top mount.
That single nut acts on the centre of a decent sized roller bearing - the bearing inner fits on the OD of the tube, the bearing outer is part of the top mount.
unfortunately the bearing is the part that is completely destroyed on mine.
i cannot work out if this is a press fit into the top mount or is fitted inside a pressed housing.
I guess its time for a new strut.. and not just the top mount :(
i will have a go at getting the bearing out - nothing to lose now i guess...
Tony