Does anyone have a simple diagram for wiring up my trans. I don't need that fancy of wirng just enough to get the overdrive working safely for a few months until I swap in an AOD trans. I have a schematic for the car but I have heard that some of the wiring could possibly be eliminated to simplify the circuit? 

Thanks

The dead simplest thing to do is take power from the ignition switch with an inline 30 amp fuse.  Run to a  SPST switch of some kind located conveniently.  I have one from radioshack that has a 12 V indicator light that shows when it is on. Then wire to the powered side of the solinoid; for a '56 that is the blue wire, '55 may be the same.  The solinoid will be fine with 12V.  That is all you need to do.

When you are driving start as normal with the OD cable pushed in. When you get to 3rd gear and the engine is racing some then you click the switch.  After that lift off the gas and if the OD and solinoid are OK the trany will shift down to OD.  When you want to disengage the OD, turn the switch off and lift off the gas. The car will freewheel.  Feed the engine some gas until you feel it start to pull and then pull the cable out. The OD is now locked out and the car will drive as a normal 3 speed.

When you forget to turn the switch off when you stop, it will be like trying to restart in second.  It probably wont hurt anything but it isn't a good idea.  Also be very careful about not reversing with the switch on. Normal 3spOD's have a mechanical block out to prevent damage but it might not work and OD does NOT work in reverse.

AS much as I hate to disagree with Ted, in this case there is a problem with the idea that you can use the govenor without the overdrive relay.  The gov allows the relay to activate by grounding the relay's coil.  It is a low amperage circuit that functions through the kickdown switch to power up the relay's coil. Wired the way Ted suggests the governor will just short out to ground when it reaches the critical speed. 

The OD solenoid is already grounded so it needs no separate ground.  The second (orange) wire  functions with the kickdown switch to short out the ignition momentarily so there is no torque from the engine so the OD can disengage hence the kickdown. 

There are two coils in the OD solenoid one is a rapid strong pull-in coil that takes a high current draw hence the 30 amp fuse. But  it is only momentary because there is a second coil that retains the solenoid engaged but draws a very few amps.

There is a very clear wiring diagram in the '56 shop manual on pg 132.  My scanner is busted so I can not post it.

http://www.hydratech.com/pctc/Public_Documents/bwwiring.pdf

Doug, feel free to disagree.  Thanks for setting me straight as I was wrong in stating that the governor is a direct wire-in as I described it.  I’ll totally agree that adding a relay to the system is the ideal method for inserting the governor back into the overdrive wiring.

You did jog my memory though on what I had originally done on my ’55 which was rewire the solenoid internally so it had it’s own dedicated ground or negative wire coming from the coil within the solenoid rather than being grounded to the case.  This simply allowed for a much less complicated wiring scheme without a relay.  At the time this was much quicker and easier than a complete rewire of that system.  This setup is still working fine after 20+ years but the weak point of this system are the breaker points within the governor with the amp load that’s applied whenever activating it.  That will eventually have to be readdressed by putting a relay put back into the system but for now, still working fine.