1988 was the switchover year to the red Apple/B&W box for the entire lineup as the Apple IIgs box and manuals underwent a similar change. Apple also overhauled manuals, switching to glossy paper (or was it the other way around, don't have my IIgs manuals handy) and dropping the "black box" Apple text on the cover. System disks also dropped the black box as well. Coincidentally the IIgs and Macintosh system software both underwent huge changes in 1988 to merit large revisions in the manuals.

I'm surprised that Apple released a new revision to the System Disk User's Guide for 6.0.4 though. Were the changes that dramatic?