Mozilla: Only ancient (1998) sources available?

Anyone have a clue why the latest at

ftp://ftp.mozilla.org/pub/mozilla/source

is from ** 1998 ** ? and where they might keep the source for anything
vaguely recent? Google searches resulted only in mirrors of this
four-year-old stuff.

I'm trying to figure out how a few things work.

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http://www.wlindley.com