I have argued with several JWs who are now being trained to deny the org ever said the end in 75, what is your approach?
Usually I show them the book God's Eternal Purpose Now Triumphing for Man's Good (1974 WTB&TS) Page 51 there is the subheading "Evening of the Seventh Creative Day begins 4026 B.C.E."
and page 131 paragraph 5 where it states,
"The first half or 'evening' period of God's seventh creative 'day' was now closing, 3,500 years from the creation of Adam and Eve. The morning of this creative 'day' was due to begin at 526 B.C.E."
This was under the heading, "Morning of the seventh Creative day begins 526 B.C.E."
and explain that from this I understand that the seventh creative day began in 4026 BCE and is 7000 year in length.
Then show page 186 where it says
"With all his earthly seed destroyed at Har-Magedon," it then asks the question "Are the original serpent and his invisible demonic seed to be left on the loose in the vicinity of our earth down to which they have been ousted from heaven? No!"
"By removing the Serpent and his demons from the nieghborhood of the earth and hurling them into the abyss and sealing them up there, bound as with chains for the next thousand years. Revelation 20:1-3 pictures this, not as a part of the war at Har-magedon, but as a follow up of that war." (Bold mine)
and then page 190 says,
"...God's seventh creative day will end up blessed, sacred, sanctified. Jehovah having blessed that day six thousand years ago..."
Explaining that 6000 years from 4026 takes you to the autumn of 1975 with the last thousand years of the devil being abyssed after Har-megedon.
This explains about the year zero
In the August 15 1968 Watchtower in the Article Why are you looking forward to 1975?
page 499
Well, for one thing, if 4026 is added to 1968 (allowing for the lack of a zero year between C.E. and B.C.E ) one gets a total of 5,993 years, come this autumn from Adam's creation. That means that, in the fall of the year 1975, a little over seven years from now..., it will be 6,000 years since the creation of Adam,
Then I say that in 1974 this was the lastest information that I believe we had, I was keeping up with my spiritual food and acting in accordance with it in pioneering.
In the September 1974 KM in the letter talking of the Divine Purpose district Assembly and this book it says,
'Have you finished reading these exciting new publications? If not, we urge you to do so without delay. Don't put this off until the material is covered in the series of public talks that are to be given. The information these books contain you need to know now.'
In the October KM 1974 there was the feature on the back page Presenting the Good News, with the "Eternal Purpose Book. Which as a pioneer I was doing and remember a fellow pioneer telling me how he had shared this good news with his study.