The information is listed in the alternative parts list on this forum. It is a 55mm x 42mm x 8mm R23 Viton double lip rotary seal, temp rated up to 200c. There are several manufacturers but a search should find a local one for you. The full instructions to replace it are on the Morgan Three Wheeler Club website but if you are not a member they cannot be accessed. Tip, the pinion nut is a LH thread.
