The Watchtower and Awake magazine volumes were reprinted in the early 1980s as Vienne has mentioned.
The Watchtowers were reprinted back to 1950 (I believe), but the Awakes only went back to 1970. At the time I wondered Why the difference? since they had long been considered 'companion' magazines.
Apparently this was the Organization's way of hiding the 1975 information because most of it was published in the Awake magazines of the late 1960s.
Information such as in this thread would now be hard for JWs to find.