KDE 3.5.10
There's a maintainer of the KDE 3.5.10 environment in rpm format targeted for use on the latest Mandriva release. (currently 2010.2)
The project is called "trinity," there are source rpms available so you should be able to get it running on fedora or suse pretty easily. You could also repackage srpms into .deb or some other format, but there's really no reason not to use Mandriva.
You can search the Mandriva forums for "trinity" or "KDE 3.5" and find the links to the packages, and some help with any glitches you may encounter.
3.5.9 was actually the last official KDE 3.5 release. People worked out the last bugs and finalized a few of the components KDE was abandoning for the 4 release and called it 3.5.10.
From what I understand it's an outstanding environment. I loved 3.5 and was reluctant to go with 4.x, but now I wouldn't trade my 4.5.5 desktop for anything, except perhaps gnome 3... running fedora 15 alpha atm and loving gnome 3 big time.
