Abstract: A power take-off shaft assembly comprises a hollow drive shaft rotatable at one speed; a drive sleeve surrounding said shaft and rotatable simultaneously at another speed; a power take-off shaft with differently splined ends each adapted to fit within the drive shaft and with a central flange having an inner circle of equally spaced holes counterbored at one side of said flange and an outer circle of equally spaced holes counterbored at the other side thereof; and stepped bolts able to reach through said holes only from the counterbored ends thereof to secure the power take-off shaft to the drive shaft when fitted in said inner circle of holes whilst one end of the power take-off shaft projects operatively, and to secure the power take-off shaft to the sleeve when fitted in said outer circle of holes after turning said shaft end-for-end so that its other end projects operatively.