David,
You have just resolved , in a moment of pure genius . a riddle that has been unsolved for me for a very long time.
The C5 Canadian Charging Panel is a portable unit and has nothing to do with the Wire 5 box, ..unfortunately.
Now, we late restorers have to find the impossible to find .
Note: I have seen such a panel with the fuses and switches in a C60 L Machinery Lorry . Not that there are many around...
Oh well. The hunt continues .