I need the source code for fedora core 5 version 2.6.18-1.2239
FC5 is a Distro.
The name is "fedora core" and the version
So I guess, from your post, that you want the source code for the 2.6.18-1.2239 kernel? (Also guessing you want the FC5 distro-kernel, perhaps as a source rpm, rather than the vanilla kernel.)
You should be able to get it from the same place you got FC5, if you got it recently. Otherwise that is a GPL violation. However, FC5 is no longer distributed by the fedora project. So getting source will be increasingly difficult.
for eg doesn't have any. FC5 is too new for there to be anything in the fedora legacy archives... they will not be added, as this project is closed.
Maintaining a legacy system basically involves moving to generic packages. So you should only do this if you have very compelling reasons.