Mayby the Columbia operates differently on the later Fords and Mercurys with the solenoid operated control valve but on the earlier ones like my 37 you can stop with it engaged,taking off is noticeable as you are in a really high gear,but you can leave it in "high" gear all day, you just want to make sure you shift back into low before you shut engine down .You must be in motion to engage the Columbia rearend.
You push in the clutch all the way down, flip the dash switch
you will hear a clunk, it is in gear.
You use this as an overdrive at higher speeds. You must disengage
prior to stopping.
Go luck.
Bob-Hampshire, Illinois
Mayby the Columbia operates differently on the later Fords and Mercurys with the solenoid operated control valve but on the earlier ones like my 37 you can stop with it engaged,taking off is noticeable as you are in a really high gear,but you can leave it in "high" gear all day, you just want to make sure you shift back into low before you shut engine down .