I was 15-16 in 1975 after having been a witness for 2 years. I was deep into the chronology bit but it wasn't 1975 that affected me, it was the 1914+generation that I emphasized to myself.
It was around 1974 that I went to a large special meeting to hear a talk given by none other than Fred Franz. In front of 10,000 people he gave a long winded talk explaining his panoramic view of history from Creation till the end times.
He explained the 7,000 year creation days and tied it in with the 6,000 year chronology starting with the creation of Adam and Eve and ending with Armageddon. He explained that there was an "Adam and Eve gap" that made the exact day or month of Armageddon impossible to predict but that the end would come within months to a few years of 1975. He specifically said it would not take decades for that to happen because that would have meant that Adam was alone for such a long period of time that he would have been "tempted into bestiality." He posed a rhetorical question saying "Would Jehovah allow Adam to be tempted into bestiality?" Then he answered his own question and said "No brothers and sisters".
I remember recording that talk but I have no idea where that tape cassette is or if I even still have it.
I also remember being in the Kingdom Hall during the theocratic ministry school when they read the Kingdom Ministry program that spoke of people selling their houses to preach in the short time available and encouraging it.
I lasted until 1980. It wasn't until a few years after I had dropped my Watchtower persona that I read detailed rebuttals by "apostates" on the entire JW Chronological voodoo. Nothing surprised me about it.