>> All of these 53 directories and 395 files seen in the MUI archive:
>> http://aminet.net/package/util/libs/mui38usr ? :)
>> Where do you have those then?

> I currently have no access to my old OS3 backup unfortunately.
> As soon as I have, I will investigate and tell here.

Result of investigation is that I remembered correctly that Libs/MUI/ was where I had all the *.mui, *.mcc and *.mcp files on OS3.x. And apparently, my system had neither a MUI: assign nor any more files from the MUI archive than the *.library files in Libs/ and the above-mentioned files in Libs/MUI/. Yet, all MUI programs worked fine.