I'm not disputing your knowledge that the pictures illustrate a Fairey overdrive.
Since power from the engine must transfer through the transmission in gear to get this device to turn. Transmission in neutral, no power going anywhere. I don't understand the OP's claim "The PTO has two gears...
To verify my searches, my question is the supply line is now the pipe on the bottom and the return is the side where my original supply was? Yes, the supply on the newer tank is the pipe on the bottom. The return (for later models) was rerouted to the side.
And the three small lines on top are...
Remember that 2 of window channel retaining screws thread into path of the glass, and require short screws. If you use the long screws by mistake, you will shatter the glass if it's in the way.
Put a piece of masking tape over the holes for the short screws so you don't forget.
Wow, three posts in and the story is starting to come together.
Whatever the source of the relay, the manufacturer should have a schematic with the information you seem to be seeking. Otherwise, pry the cover off and figure it out.
Wiring diagram from Cruiser Wiring - http://www.globalsoftware-inc.com/coolerman/fj40/wiringmainframe.htm
Thank @Coolerman for his efforts on building his website, and buy your wiring supplies from his online store.
Item 12 is the horn relay near the bottom left shows H: green/white trace; B...
The fiche card shows cover 51495 fastened with 91651-40825 screws.
Those screws are M8 x 1.25 x 25mm long with integral lock and flat washers made from low/medium strength carbon steel.