General San Martín Railroad's ALCo. RSD16 #8484 heads a six-car commuter train ready to leave Retiro Terminal. The General San Martín RR. operated its 75 RSD16's in all kind of duties: commuter and intercity passenger services, and merchandise, oil, wine, peddler and way freight. This interchangeability allowed enthusiasts the chance of watch certain gadgets not easily found in Buenos Aires, like the modified knuckle coupler applied to # 8484, which both served as a pure knuckle in oil-train consists with tank cars fitted with knuckle couplers, and as a hook-and-screw coupler by means of the retracting chain hanging from the knuckle side.