The following might do: Red Hat Enterprise Linux - Wikipedia, the free encyclopedia
Releases and their available RHEL kernel versions are listed at the end. The same kernel versions are available for x86 and x64. As far as I know support for IA-64 (Titanium) has been dropped with RHEL 6.
If you are looking for Enterprise Linux that supports a very recent version of the mainline kernel, check out Oracle Linux UEK kernel, currently UEK3 is based on 3.8.13. It's also free including updates. I'm not sure if it is "unbreakable", but you can't beat it's price/performance ratio.