Is there an extension or something that I can put on the System 7.5NAD disk so itll recognize the HD20?

Reason I ask, is I want to backup the entire HD20 that I have before it eventually fails, but the 7.5NAD disk doesnt recognize it. The system will boot from the HD20 of course, but its running an OS that I cannot get to recognize appleshare localtalk. I think it was System 5, it might even be an early System 6

Using a macintosh SE