It helps to play with “physical” parts when one is not used to read high level engineering plans provided in this forum.
So I did very quick 3D STL drafts of the Reisenauer chief, flange, 10mm shaft, bearing, lip seal… for you to play finding out about volumes, dimensions, shaft length adjustments, etc…
The thread for the shaft is 1.5 whereas the real one is 1.0, that is for schools projects as 1.0 shafts are difficult to source.
The inside of the Reisenauer is totally empty and does not show any gear nor rotating stuff.
Here is an out-of-the-blue invented flange for a 620KV aquastar motor for instance
Then here is a 10mm shaft with a x1.5 thread on each tip. The shortest threaded tip is supposed to be screwed into the Reisenauer Chief shaft “plug”
Then a typical 10mm lip seal
A typical 10mm ceramic bearing
A rough copy of the 39mm 620KV aquastar
A 40x45mm tube with a side open to allow for visualization of what is inside the tube