the 2 axle box car was the fundamental rolling stock of the JNR freight service from the 1920s through the 1980s......even after the devastation of WWll, 40000+ of the ubiquitous carriers were constructed and remained in service until the containerization revolution forced obsolescence.......fundamentally, most of these wagons had a maximum operating speed of 75 kph while carrying a maximum load of 15 tons.......every major JNR fabrication partner participated in the post WWll rebuild - kawasaki, nippon sharyo, mitsubishi, hitachi........the wamu70000 variant was an all steel wagon to facilitate palletized handling of cargo; the design also incorporated a kc type automatic air brake...... 5710 cars were produced between 1958 and 1960 around the normal performance parameters......of course, even the improved efficiency of palletized handling did not delay obsolescence coincident with the triumph of containerization and the decentralization of JNR into the 6 privatized regional railways.....