That will be No61. Which will have little effect on the puddle of oil under your bike. The only way to stop that is to fit a sealed bearing 57 inside the box. Ron
Part is 24-4232 where does this go? Its not arrived yet so unsure on the diameter until its in my hand so does it go under the sprocket or on the other side where the locking nut is? Also part 57 on the diagram has come as a sealed bearing so that should help
It's not obvious from the drawing Tod, but it goes over the mainshaft and sits against the nose of the sleeve gear. The sleeve gear should have a taper in the bronze bush to accept it.
As Ron mentions it won't stop the drips.
A double sealed ball race bearing is the best bet to reduce the drips.