I had to do this due to a foul on my wbx6 between one regulator mounting screw and the inlet manifold (which could have then cracked the plastic) the benefit being that you can change the brush pack without removing the alternator. Might be of use to other wbx owners?
The basics: remove alternator, remove the four screws that hold the casing halves together, rotate rear housing and windings *as one* by 90 degrees, replace screws.
Charging cable and warning lamp terminals are still easily accessible.

1985 Oettinger 3.2 Caravelle RHD syncro twin slider. SA Microbus bumpers, duplex winch system, ARC 7X15 period alloys