This is what the book From Paradise Lost to Paradise Regained WT. 1958 says on page 197
'The great crowd has "come out of the great tribulation." This is the great tribulation or trouble that Jesus said would mark this "time of the end." This tribulation began on the Devil's organization A.D. 1914 When Jehovah's newly enthroned King took was action against his enemies in heaven. ( From Paradise Lost to Paradise Regained WT. 1958)'
This would have been about the time my parents became JW and so they would have believed they would not die of old age as the Watchtower March 15. 1965 on page 177 speaking of the great crowd
'They will never go to Hades or Sheol and need to be resurrected.'
When the understanding changed regarding the tribulation and the time interval between the first part and the second part with a gap in the middle a suggestion made in 1925. The Watchtower of January 15th 1970 page 53 says
'Then the time interval between the opening part of the "great tribulation" and the closing Armageddon part thereof will prove to be around five times as long as the length of the "great tribulation" itself.'
This 'will prove to be around five times as long' I believe is a reference to 1975. Which my father certainly thought was the date that the end would come by. If not they still had the generation.
Then in 1995 that was taken away. Now he needs the resurrection.