I really believe AMC was the last holdout with factory-available overdrive through about 1965 or '66. The "Twin Stick" was a three speed stick on the left with an Overdrive In/Out lever on the right.

Earlier cars of all makes/models usually had a chrome handle to push/pull that engaged or disengaged the lockout on the overdrive unit.

I've seen Columbia unit's from the 40's that were electric and had a toggle switch under the dash labelled "Columbia Overdrive".

Can't say as I've ever seen one mated to an automatic, but also remember, the bulk of Automatics back in the 40's and through most of the 50's was GM's 4-speed Hydramatic. IIRC the top gear was a mild overdrive.

At any rate, to operate one was just like operating your average three speed manual. However, when you got up to highway speed, or generally anything over 40mph, push in the lockout handle (to allow the OD to engage) then lift your foot off the gas lightly and hold to allow the OD to fully engage.

The AMC/Rambler Twin Stick was a little more user friendly engaging OD almost instantly when the lever was moved to the "IN" position. There was no lag or waiting time to allow the OD to engage. There was even an electric disconnect button on top of the three speed shifter that, when pressed would instantly disengage the OD for passing or shifting down into second. The Twin Stick could also be operated at almost any speed as long as the transmission was in either of the top two gears, essentially creating a 5 speed.
(1-2-OD2-3-OD3)

Could you imagine split-shifting a Rambler?



AMC brought back a fully electric Overdrive with a Laycock-deNormanville unit from France and it was available on 6-cylinder Gremlins, Hornets and Pacers with the 3-speed. A button on the end of the turn signal wand engaged OD. These were short-lived because LdN couldn't keep up with the demand of orders AMC was placing and the option was cancelled after only a year. (Late '74 to mid-year '75)