Exactly. You might say Slackware doesn't really need one.

All scripts live in /etc/rc.d/ - there are no other directories containing symlinks, no Sdd or Kdd scripts, nada. We get an rc.S (for single user, or runlevel 1), an rc.M (multiuser, or runlevel 3), an rc.4 that launches (x|g|k)dm, an rc.6, an rc.K, and other daemon scripts like rc.httpd, rc.mysqld, rc.inetd, rc.samba, rc.sshd, etc.