A robotic surgical tool comprises a lead screw and at least one spline extending between first and second end, and a drive puck movably mounted to the lead screw and the spline and movable between the first and second ends. A spline coupling is rotatably coupled to the drive puck and receives the spline such that rotation of the spline correspondingly rotates the spline coupling. An instrument drive output is rotatably coupled to the drive puck and operatively coupled to the spline coupling, such that rotation of the spline coupling correspondingly rotates the instrument drive output. A drive housing is mountable to the drive puck and includes a drive input rotatably mounted to the drive housing and matable with the instrument drive output such that rotation of the instrument drive output correspondingly rotates the drive input.