I have an acquaintance here in the Bay Area who is into vintage VW buses....his website ratwell.com is phenomenal and I found these clamps referenced there. They can be obtained directly from the Ultimate Garage...
All parts 304 stainless steel, no worm drive perforations, hex head screws, rolled edges...
Look at the data for the ABA 304 Mini Clamps. Another thing I like is that this is the only resource I have seen that indicates a torque value for this important connection.
http://www.ultimategarage.com/abaprice.html
Ever seen anything better?