Yep, good score on the 'green book'.
The story on the publication dates is that it first came out in 1968, as you say, and supplements came out each year to update it with the new models. As Jack says, that's why it's a ring binder format, with a lot of rings to stand up to heavy use.
Updated/corrected pages for the earlier models were also supplied to Victa's dealers, and these will have a publication date footer on them. Anything without the revision date on it is original 1968.
There is also a 'Volume 2', which covered the 1972-3 and 1973-4 models.
The updates to include Victacodes came out in latish 1970, as near as we can judge.
