Apparatus and methods are for coupling a drive unit to a tool adapter. A drive unit includes a drive stem; a plurality of sliding coupling members; a retainer; a torque profile; a plurality of drive stem ports; a coupling collar; coupling recesses; a plurality of transmission units; and/or first portions of a hydraulic coupling unit. A tool adapter includes a tool stem; a tool stem sleeve; coupling recesses; a torque profile; a plurality of sliding coupling members; and/or second portions of the hydraulic coupling unit. A method of coupling a drive unit to a tool adapter includes positioning the tool adapter below the drive unit; stabbing a drive stem into an interior of a tool stem sleeve; coupling torque between the drive unit and the tool adapter; and coupling load between the drive unit and the tool adapter by engaging a plurality of sliding coupling members.