Allan, you're speaking of fitting a 1941-to-1952 transmission + overdrive to the 1940 car?

Didn't the 1940 car come equipped for the 1-lever + cable linkage? And aren't all of the transmissions 1940 to 1952, of the lever + cable design? If so, I would assume that the 1940 column is all set up for it.

Allan,
I put a 1950 transmission with overdrive into a 1940. There is no need to change the column. To fit the transmission you will need to cut the X frame and shorten the drive shaft to accommodate for the larger transmission. It works well though.

Allan, what wheel base do you have?. I think if it is a custom, it fits with no problems. We have found you need to change the angle from the shifter rod to the trans slightly. If you have any questions, feel free to email me at my regular address. Thanks Doug

Doug, it's a Super. I'm only worried about the shift rods from the stock car working on the later single lever overdrive.

I'm not sure what you are trying to accomplish?. Are you talking about adding a later model ,say like an R-9 or R-10 overdrive unit, unbolt it from its original case, then mate it to the original case in your car?.
Something to point out here, it has been mentioned the first year for column shift is 1939. Even though the floor shifter is no longer required, the transmission is still of the old design. Hudson modified the top cover of the old trans. ,making the cover contain partial pieces to make it shift., thus creating the first year for a shift gate cable. This cable actuates the gates, 1-R or 2-3. 1940 was the last year for this design, which Hudson used for close to 10 years. A completely new design for '41 .
With that said, why not search for a single lever trans., with O/dr. and fit that into the car?. It would require a '41 to '47 bell-housing and rear support plate, the clutch bell-crank from a '41-'47.
If you want a car with a floor shifter, you can then install a T-86e, purchase a shifter from one of the Jeep warehouses. When trying to mate your splasher engine to the problem with this is the configuration of the rear support plate and bolt pattern will not line up correctly to the double lever trans., starter location,etc. and requires other modifications