Where do you see various trees-branches?

Because (the suggestion is too obvious, and therefore already failed?) the filename points exactly to GECKO 1.9.2.3 20100401 branch.

I can see 1.9.2 branch, but nothing more definite than that:
http://mxr.mozilla.org/mozilla1.9.2/source/

And even xulrunner misses 1.9.2.3 release:
ftp://ftp.mozilla.org/pub/mozilla.or...nner/releases/

And mozilla has only old releases:
ftp://ftp.mozilla.org/pub/mozilla.org/mozilla/releases/

[EDIT] It is rumoured that Firefox 3.6.3 is the one needed:
ftp://ftp.mozilla.org/pub/mozilla.or.../3.6.3/source/
Try it?
[/EDIT]