The original vented # plate made specificly for our trikes was manufactuered by UFO designs in Huntington Beach CA.
Ofcourse, they are no longer made, but this is the guy that made them(it's a small shop).
hemant@ufodesign.com
Please email them and ask about the old # plates.
Lets at least get a small run of these things made again (in both green and red!) get sending those polite emails!