judge

Which scriptures did Josephus use?
It seems that there may be evidence he was aware of variants in his day according to the this link which states...

.. It has been suggested, for instance, that the Jewish historian of the first century A.D. Josephus "confirms the chronology of the LXX" (Zurcher 1960, p. 60) in the sense that the years of the antediluvian patriarchs are 2,656 years (Ant. I.3.3-4), which is exactly 1,000 more than in the Hebrew text (MT) and relatively close to the figure of the LXX (Alexandrian text), which has 2,262 years to the flood. In actual fact, however, Josephus contradicts himself at several points.

Jayhawker Soule

The statement:

"A.F. Jones has argued on the ground that the figure 2,656 is but a confusion of the 1,656 of the Hebrew, and that Josephus "was perfectly familiar with the figures of the Hebrew version ...

seems to pose a false dichotomy between "the Hebrew version" and a Greek version, as if there was no Hebrew Vorlage of the Septuagint. The DSS, however, attest to what Tov terms a pluriformity of textual variants, and he notes that "texts that are close to [the Septuagint] comprise some 5 percent of the Qumran biblical texts." [from Textual Criticism of the Hebrew Bible]