Steve, I believe the original equipment was a "Headfoil" system. Several years ago I replaced the plastic extrusion on Mondial. I called the Headfoil office and found them to be both very knowledgeable about the original J/30 specs as well as very helpful. Here's the contact information from the "Marketplace" page:
http://www.headfoil.com Headfoil Corp.
P.O. Box 449
Lake City, MN 55041
Mary Lagerquist
(612) 345-4115
