http://support.apple.com/kb/TA28558?viewlocale=en_US
They made 6.0.8L primarily for the Macintosh Classic II and Macintosh PowerBook 100. I remember reading that it was because System 6 had a 8MB limitation, so they made 6.0.8L so it could address the Classic II's ability to hold 10MB. (Probably more reasons than just that.)