They started touting 1975 in 1966, with the realease of the book Life Everlasting in Freedom of the Sons of God. (The offending words may be found on page 29 of that book. ) This happened at least five years before Raymond Franz was appointed to the GB.
No, the 1975 debacle originated with his uncle, the WTS's resident madman theologian , Frederick Franz. (FW Franz wrote all their books in those years. This showed up in his writing style, as well as in his kooky ideas!)
When 1975 proved to be a non-event, the WTS then tried to blame it on just about everbody but the actual culprit.
All this reminds me of the typical six stages of a project:
1) Wild enthusiasm
2) Deep despair
3) Panic
4) Search for the guilty
5) Punishment of the innocent
6) Promotion for those not involved.
Although this saying was intended to be presented in a tongue in cheek manner only, I still do believe we saw all six stages happen amongst the JWs over the matter of 1975!
Bill.