An end-on view. Note the curved caps, the location of the solder and the cap which has a tag folded back on itself. Note the two round indentations in the metal housing. These mark the top - ie, the motor should fit in the chassis with these pointing upwards. And yes, it does matter - if it is placed upside down, the chassis contacts the wrong brush, and the train will run backwards when all the others on your layout run forwards.