Can anyone identify this reg/rect?

This looks like a very nicely made regulator/rectifier that came with the cafe project. As far as I am aware it is fully working,but it would be good to know if anybody can identify it's origins as I have never seen one like it before.I imagine that it is specific for the Guzzi Bosch alternator system or maybe it's for another make of bike?  I guess even some very clever person could have made it in their shed!