I'm working with a GeoJSON file that contains sets of coordinates associated with street corners in the city of Montreal, Canada. The spec sheet of the API delivering those GeoJSON specifies that the coordinate system uses the NAD31 projection datum, which in spite of my search I doubt exist.
Because of the street names associated to the coordinates in the GeoJSON, I am able to deduce that the erroneous NAD31 coordinates
300247.509025, 5040897.253 refer to the WGS84 latitude/longitude
Does anybody know what might the geodetic datum NAD31 refer to, and how I can convert it to WGS84 coordinates?