I have the Spanish version of the most recent CD ROM and does not go any further back to 1970. I found an article entitled "THE 1,000 YEAR PEACE IS AT HAND OR IS APPROACHING" something like that, (REMEMBER I AM TRANSLATING), and gives a similar information. Back then the spanish speaking will receive the information like 4 - 6 months later than the english speaking so the date might not be the same. In spanish, the article came out in the April 1, 1970 Watchtower, maybe is the same, but look back 4-6 months and try to search for that article.
I will try to translate to the best of my ability one paragrapah where it is suggested, almost openly said that the mid 1970's will be the time of the end.
Paragraph 40
Ya dentro de poco, seis milenios de su inicua explotación de la humanidad como esclavos suyos terminarán, dentro de la vida de la generación que ha presenciado los sucesos mundiales desde el fin de los Tiempos de los Gentiles en 1914 hasta ahora, conforme a las palabras proféticas de Jesús en Mateo 24:34. Bueno, pues, ¿no sería el fin de seis milenios de laboriosa esclavitud de la humanidad bajo Satanás el Diablo el tiempo apropiado para que Jehová Dios introdujera un milenio sabático para todas sus criaturas humanas? ¡Sí por cierto! Y su Rey Jesucristo será Señor de ese Sábado. (THE FIRST SENTENCE IS TALKING ABOUT SATAN)
"SOON, 6,000 YEARS OF HIS WICKED EXPLOITATION OF HUMAN BEINGS AS HIS SLAVES WILL END, WITHIN THE LIFETIME OF THE GENERATION THAT WITNESSED THE WORLD EVENTS SINCE THE END OF THE GENTILE TIMES IN 1914 UNTIL NOW, ACCORDING TO THE PROPHETIC WORDS OF JESUS IN MATTHEW 24:34. WHY THEN, WOULDN'T THE END OF THE 6,000 YEARS OF HUMANKIND HARD SLAVERY UNDER SATAN THE DEVIL, BE THE APPROPRIATE TIME FOR JEHOVAH GOD TO INTRODUCE A 1,000 YEAR SABBATH FOR ALL HIS HUMAN CREATURES? OF COURSE! AND HIS KING, CHRIST JESUS WILL BE LORD OF THE SABBATH."