Abstract: A power driven socket wrench is assembled with the drive adaptor by positioning a rotary output shaft on the drive adaptor in coupled engagement in a rotary drive socket journaled in the wrench housing and swiveling the wrench about the axis of the output shaft to position a single clamping screw, threadably engaged with the drive adaptor, within an arcuate slot in the wrench housing. The slot has a center of curvature coincident with the axis of the drive socket and opens through one side of the wrench housing. The wrench unit seats in a shallow channel in the drive adaptor and may be connected with or removed from the drive adaptor by loosening the clamping screw which remains connected to the drive adaptor.