Here is an informed Orthodox Christian discussion of the issue:
http://www.monachos.net/forum/showthread.php?6922-Jewish-claims-about-the-Septuagint-Pentateuch-only
The real problem is that there was not one “Judaism” before Jesus and at the time of His earthly ministry, but several streams of Judaism. The Septuagint (meaning the entire Greek Bible) was a Hellenistic Jewish book, not a Rabbinic Jewish book.
Rabbinic Judaism, as it emerged after 70 AD, refused to acknowledge the Septuagint because of Christian use of it as a book of prophecy. Hence the idea that the “real Septuagint” included only the Pentateuch.
However, to this day, we Orthodox Christians see even the Pentateuch, in its Septuagint version, as containing prophecies of Christ, and we use it that way in our liturgies.
Most of what I know about prophecy I learned from Jewish Rabbinical teachings. I will never convert because they place the Talmud(oral law) above Torah(YHVH’s law), but to deny their historical accounts of prophecy is to deny the devout Jewish writers who wrote them. In fact, the parables Yah;shua the Messiah spoke came right out of Rabbinic parable teachings.
You may want to rethink what you said and then actually take a read of Rabbinic prophecy & parable teachings.