I have a flathead jack 3/4 race 8aba flathead that I just finished building for my 1951 mercury custom. I have the origonal overdrive transmission in the car. The person I bought the car from had disconnected and abandoned all of the overdrive components, so the car was out of overdrive when ever I drove it. On the freeway it sounded like it was going to grenade on me. I have found all of the missing parts from Mr. Merc. I will be installing all of the parts soon. Problem is...Nobody can tell me how to engage, and disengage the overdrive. There is a kickdown switch under the gas pedal, a relay on the firewall, a pull handle under the dash, and a governor on the trans. When do I pull the handle, and when do I push it in. Is there a simpler way to do this?