I´ve just installed two mono tube plates myself,use them as a stereo.
Take about BIG sound,love them.
I can really recommened to get Cunninghams tuning kit for them.
The main plug is called "ironing socket" here in sweden
as was very common in the old days used for roasters,ironings e.t.c.
I managed to found one here at a electronic shop it was his last
and he said he couldn´t get anymore.
Replace them or look in second hand shops/flee markets.
They are big and are partly made of porcelain.
The biggest of the circular connector is for the remote
if they don´t have any remotes and motors don´t mind those.
If you need them they are very expensive(200€ at least)
because they are the same as for neumann mics.
I had only on of them and on the other plate I used small "sockets" for every pin instead.
worked well.
The smaller circular connector is for audio I/O
those you should be able to find on ebay.
I have the pinouts for both sockets if you need.