PDP-8/M AC input for 240VAC?

[Wai-Sun Chia]

Hello list,
Just finished my H786 restoration on my BA11-N box (thanks Tony!) and 
now moving on the my PDP-8/M.

First things first, how do you convert between 115/240VAC on the -8/M? 
There are no jumpers on the transformer and AFAIK the H740 is not a 
ferro-resonant (thank $(deity)) type..

Does the 240VAC come with another AC input box (BC20-A)?

If so the question now boils down to:
What is the diff between a 240VAC and 115VAC BC20-A?


/wai-sun