The tool includes a housing having two substantially semi-cylindrical members. An air motor in the housing has motor end members located adjacent each end thereof. Two O-rings, respectively disposed between the motor and the end members, are squeezable axially so as to be forced radially outwardly to abut the housing. A manifold includes a chamber of a size that dampens Helmholtz frequencies in the exhaust air. A bearing block includes an outer surface configured to transfer operating loads from a crank shaft extending through the bearing block to the housing. Each of the members of the housing has an arm with a cylindrical opening for receiving a rotatable drive body. The drive body has a knob including a shaft having an ear cooperating with an O-ring in the drive body for preventing the knob from inadvertently rotating between operating positions while the tool is in use. An O-ring between the knob and the drive body isolates the housing from shock to the knob resulting when the tool is dropped. A bushing disposed within the opening of one of the arms includes an outer surface having a plurality of serrations to provide a secure fit between the bushing and the arm. A washer and a retaining ring are located adjacent the bushing. A spring is located between the bushing and the retaining ring for biasing the drive body against the arm to provide friction between the drive body and the arm. An elastomeric jacket surrounds the housing.