An adjustable bent housing includes a tubular member with a first engagement means and an adjustment ring with a second engagement means. The first engagement means has a plurality of sockets in a first region of the annular end face of the tubular member, and a plurality of locking pins projecting from a second region of the end face. The second engagement means has a plurality of sockets in an annular end face of the adjustment ring, configured to receive the locking pins. The second engagement means further includes an indexing pin projecting from the adjustment ring end face, and receivable within any socket of the first engagement means when the locking pins are disposed within corresponding sockets of the second engagement means. The adjustment ring is longitudinally movable relative to the tubular member to permit relative rotational adjustment therebetween and configured to prevent over-rotation of the adjustment ring.