Just one example, from WT 1966 Oct 15, pp. 628 -629:
"President Knorr, "a new book in English, entitled 'Life Everlasting-in Freedom of the Sons of God,' has been published." At all assembly points where it was released, the book was received enthusiastically. Crowds gathered around stands and soon supplies of the book were depleted. Immediately its contents were examined. It did not take the brothers very long to find the chart beginning on page 31, showing that 6,000 years of man's existence end in 1975. Discussion of 1975 overshadowed about everything else. "The new book compels us to realize that Armageddon is, in fact, very close indeed," said a conventioner. Surely it was one of the outstanding blessings to be carried home!"
There are other examples, too, where 1975 IS mentioned as THE date.
Grace