To make it easier for you I've taken a few pictures tonight the cab was chassis mount stepdown converted by the previous owner, the line filter had screw terminals so no wiring was cut.So you have two plugs to the wall? one for the 4 way extension and one from the cab for lights etc?
or did you wire that into the line filter, either way it looks pretty tidy inside.
I really want to find someone of those 1P 2P stickers
Also as I don't like marquee holders I've added a cover made from a sheet of magnetic plastic to cover the hole at the back & keep out dirt ect I'm also missing a monitor cover cap.