rewrite ^/showthread.php /showthread.php; rewrite ^/forumdisplay.php /forumdisplay.php;
RewriteRule ^/old-dir/showthread.php /new-dir/showthread.php RewriteRule ^/old-dir/forumdisplay.php /new-dir/forumdisplay.php
RewriteRule ^/old-dir/threads/ /new-dir/threads RewriteRule ^/old-dir/forums/ /new-dir/forums