Very late but better late than never . the shoulder boards are certainly argentinians and a rather uncommon model the rank of the wearer is lieutnant general the highest of the argentinian army three pips here called suns ,red backing and gold braid of fine quality . this shoulder board type were for use with the full dress uniform ; they are of about 1924 to 1927 later the model was changed to a german style triple gold cord interwoven shoulder boards on red backing and with the same pips And yes the argentinian army received german influence between 1896 and 1940 in many ways including weapons until the ww1 ,doctrine uniforms , organization,and so on .