A few links to audio recordings of 1970's convention talks where 1975 was highlighted.
http://www.jehovahs-witness.com/topic/104490002/you-will-never-grow-old-this-current-system-things-awake-may-22-1969-p-15?size=20&page=3
What would you be expecting to happen after listening to the following convention statements between 1968 and 1975, year after year? These comments were all bellowed from the platforms, sometimes by the GB themselves, to packed arenas...
"It almost seems as though Jehovah has provided
meat in due season because he has held up before all of us a new goal, a new
year, something to reach out for and it just seems it's given us so much more
energy and power in this final burst of
speed to the finish line. And that's the year 1975."
"There's only 8 years until '75. How little time
there is left"
"We're going to listen to [the Societies] agonizing
entreaties "Brothers get in" because they know what's coming. And it's coming fast and don't wait until '75.
The door's going to be shut before then."
"As one brother put it, 'Stay alive 'til '75'"
"Not really a full 83
months remains,
so let's be faithful and confident and we will be alive beyond the war of Babylon;
we will be alive beyond the war of Armageddon" (spoken in Nov 1968, so 83 months later would be Oct 1975)
"What are you going to do with China, how are you
going to get into China, how will you have reached all those people there, how are we ever going to reach them by 1975?"
"There are a dozen inexorable forces at work
right now that are converging together inside
of this decade that will spell disaster for this system of things, and
there is nothing that no human can do to prevent it"
"We had that advice about 1975, Not changing a
thing! Not changing a thing!... We have stronger reason to see that the middle
70's are going to see the complete change in earths affairs"
"Now our enquiries around the world of the brothers as to what they're
expecting to occur between now and the end of 1975 has revealed that some are
very sanguine about matters in the near future, and they're expecting the great
tribulation to occur, and the destruction
of Babylon the Great, and the annihilation of all the political systems of this
world, and then the binding Satan and his demons and their abyssing, to occur
before this year is ended, this year 1975"