I have '40 steering gear in my '36, which is the same size, length as a '37-40. I used a '40 column because I have a column shift trans, only alteration was to re-position the column drop by about 1/2" which required re-drilling the lock hole in the column.
If you are replacing the steering gear do as 'jondee1' suggested.. Any '37-39 column jacket will work if you want to keep the headlight switch on the steering wheel.
I upgraded my lights to a pull switch on the dash and a floor mounted dimmer switch.