It is DFS 2.45, but this time it's dated 1989. It seems a bit odd that MOS 3.50, which came out in 1989, would have a 1985 DFS in it, which also exists in the same version number but with a different date. The differences are only minor, a couple of dozen bytes in all, and whilst I haven't done any testing, it could just be an update for new floppy drive timings available to the 1772 controller which was introduced in place of the 1770 at around this time.