Originally Posted by astrogeek
You can easily rebuild the tar package using the original slackbuild from the source tree.
In addition, according to UPGRADE.TXT
in the Slackware 13.0 file tree, you may just upgrade pkgtools, tar and install xz packages directly, without rebuilding (if the dependencies are is met) and it makes installing/reinstalling/upgrading/removing the txz packages without any problems. But it possibly if you use Slackware 12.2, not 12.1, else you should be rebuilt these packages before.