An adapter and adapter assembly for a torquing tool includes a reversible adapter and a sleeve having an adjustable extension member. The adjustable extension member joins the sleeve to the power unit and accommodates a range of drill bit lengths when the adapter is in a fastener driver mode. The adapter is reversible within the sleeve and includes an elongated body having a bore at one end to accommodate a working member such as a drill bit and a bore at the other end to accommodate a fastener driver. The adapter body includes an internally tapped bore threadably accommodating a set screw against which the driver abuts. This provides a depth adjustment for the driver. Grooves are provided for detachable connection to the sleeve. A quick release means housed within the adapter detachably retains the working member within the bore and to the elongated body and means associated with said bore and said working member for transmitting torque from the tool to the working member. The preferred quick release means is a spring loaded shuttle positioned in an opening radially through the body member and in communication with the bore. The preferred torque transmitting means is a pair of corresponding, opposed surfaces disposed on the bore and working member respectively.