As +Greg Kroah-Hartman has EOL'ed Linux Kernel 3.8.x starting from 3.8.13, there are no LTS support for any modern Linux Kernel releases since Greg are maintaining two kernel version already and he didn't want to add the third one (not until he released one of them).
Slackware Linux is planning to use Linux Kernel 3.8.x for their default kernel stock in their next release (don't ask when. IT WILL BE RELEASED WHEN IT'S READY), but doubt has rising in since the kernel has been EOL'ed and that means no further support for this tree, which is no good for a distribution.
Ubuntu Kernel Team is stepping forward to take care of the Linux Kernel 3.8.x branch since they used the same kernel version for their 13.04 Ubuntu Linux until August 2014. More information about Ubuntu's approach can be seen on their wiki page.
Hopefully Pat is convinced with this good news and keep 3.8.x for the next Slackware release and not using the old 3.4.x (which has LTS support from Greg).