A housing, mandrel and bearing assembly positionable in a wellbore includes a torque transmission member adapted to connect to a source of rotational torque (e.g. a downhole motor power output) and a tubular mandrel adapted to connect to a drill bit. A lower tubular housing is adapted to contain a lower bearing and catch sleeve assembly. The catch assembly is adapted to retain the mandrel in the lower housing if the mandrel breaks. An upper tubular housing contains an upper bearing and is adapted to connect to a housing of the downhole motor. A method of assembling the downhole housing, mandrel and bearing assembly is disclosed.