I think they're called "Primer Nationals" and you can view their website here
www.primernationals.com
And then there are these "rat rod" shows
http://www.hunnertcarpileup.com/main.php
http://www.vivalasvegas.net/
"Rat rods" usually go together with the "rockabilly" culture. Kind of a complicated thing, they're all about they're "old school culture".
Mike