System 6.0.6

System 6.0.6 (Finder 6.1.6, System Software Update 6.0.6) was never fully released, as internal testing revealed an AppleTalk bug. It was slated for release on October 15, 1990 with added hardware support for the Macintosh LC, IIsi and Classic, but was superseded by System 6.0.7 which was published later the same day with AppleTalk fixed.