You may have a Truckstell "Tip-toe-matic" overdrive; a dealer and up-fitter option installed in Chevy cars (mostly) from 46-54, although I have read of some being found in 1/2 ton suburbans and pickups.
Look. Good find! I wish I had one to "try" and install in the front torque-tube driveshaft of my 3600.
I hope it works!!
