My beat-up copy of the RPI compendium of railroad data has 1950 as the change to the wording within the circle herald to "Bridge Line to New England and Canada." The previous round herald had "A Century of Anthracite Service" according to the Bridge Line Historical Society.
RPI has 1963 as the change to the shield herald.
Kadee just released a fifty foot boxcar (Their Catalog Number 6403) with the round herald. The build date was 1956.
