X11R6 / lib / libXext.6.dylib

Where Do I find this library???
i'm dl'ing .pkg's off the site & some require this
/usr/X11R6/lib/libXext.6.dylib
nothing seems to install it??
or aren't I installing the right things??

I believe X11R6 installs that library.

:-/ k thanks I did install it but a lot of binaries still cannot find it ^^ anyhow, over that now doing other stuff on my mac... thanks