thanks for all the response guys! i went through and after calling around nissan in the US they located 2 parts, one in missouri and tennessee... I quickly overnighted the part monday morning and recieved it the next day.. to my surprise it its the plunger assembly to the carb, or what i believe... now i dont know if the part number on the exploded diagram is correct...
http://www.carpartsmanual.com/datsun520/Datsun520521Index/Engine1300J13/Carburetor/ExcLtuToApr68/tabid/1371/Default.aspx
number 45 is what i needed
ugh!.. 20 for the part, 30 for the overnight shipping. = 520 still dead and , has to be moved by friday, i guess tow truck fees +