An electrical connector interface comprising: a plug connector assembly including a plurality of spaced apart conductive contact sockets , each contact socket having a mating end retained in a monolithic mating portion of a nonconductive plug shell body , the nonconductive plug shell body having an external mounting flange with a plug anti-rotation aperture having a first non-round anti-rotation portion ; a receptacle connector assembly including a plurality of spaced apart conductive contact pins extending into a mating portion of a nonconductive receptacle shell body , each conductive contact pin having a mating end configured to engage respective mating ends of the spaced apart plurality of conductive contact sockets, the nonconductive receptacle shell body having an external mounting flange with a receptacle anti-rotation aperture ; and an anti-rotation fastener post with a first fastener receiving end opposite a second fastener receiving end , and characterized by the receptacle anti-rotation aperture having a second non-round anti-rotation portion ; wherein said anti-rotation fastener post is reversible in that, in a first post orientation, the first fastener receiving end is insertable into the receptacle mounting flange and, in a second post orientation, the first fastener receiving end is insertable into the plug mounting flange ; wherein the first fastener receiving end includes a non-round external surface insertable into the first non-round anti-rotation portion from an inner mating side of the plug anti-rotation aperture in the second post orientation, and the second non-round anti-rotation portion of the receptacle anti-rotation aperture in the first post orientation. a plug connector assembly including a plurality of spaced apart conductive contact sockets , each contact socket having a mating end retained in a monolithic mating portion of a nonconductive plug shell body , the nonconductive plug shell body having an external mounting flange with a plug anti-rotation aperture having a first non-round anti-rotation portion ; a receptacle connector assembly including a plurality of spaced apart conductive contact pins extending into a mating portion of a nonconductive receptacle shell body , each conductive contact pin having a mating end configured to engage respective mating ends of the spaced apart plurality of conductive contact sockets, the nonconductive receptacle shell body having an external mounting flange with a receptacle anti-rotation aperture ; and an anti-rotation fastener post with a first fastener receiving end opposite a second fastener receiving end , and characterized by the receptacle anti-rotation aperture having a second non-round anti-rotation portion ; wherein said anti-rotation fastener post is reversible in that, in a first post orientation, the first fastener receiving end is insertable into the receptacle mounting flange and, in a second post orientation, the first fastener receiving end is insertable into the plug mounting flange ; wherein the first fastener receiving end includes a non-round external surface insertable into the first non-round anti-rotation portion from an inner mating side of the plug anti-rotation aperture in the second post orientation, and the second non-round anti-rotation portion of the receptacle anti-rotation aperture in the first post orientation. <EOS>