A gear change actuator (40) including first and second rotary members (54) each rotatable in opposite first and second directions, the rotary members (54) engaged with a select unit (60), which is engaged with an output member (162) having an output axis. The select unit (60) has opposite first and second input motions, and opposite third and fourth input motions, induced by simultaneous rotation of the first and second rotary members (54. The select unit (60) has opposite first and second output movements that are transmutations of the select unit (60) first and second input motions, respectively. The select unit (60) also has opposite third and fourth output movements that are transmutations of the select unit third and fourth input motions, respectively. The output member (162) has movements, respectively imparted by the select unit (60) output movements, that are one of rotationally about the output axis and axially along the output axis.