Whilst I was having my saildrive gaiter needlessly changed in France (15 years old and still perfect) I decided to drop the rudder and fit a new Jefa lower bearing.
Unfortunately the Parklev dropped the stern of my boat through a radius instead of vertically and it tore the seal that sits at the top of a rudder tube mounted to a grp tube in the transom.
My UK yard gave me the name of a UK supplier and £8.50 later it's as good as new.
Hope someone finds this useful in the future.
9cm outside measurement, 6cm inside.
I replaced mine on a B42 with like for like a couple or £ on the internet. Then realised I could have put a double seal in for just a few £ more. double seals do not have the metal work and springs open to the elements. Type "water shaft seals" into Google.