RE: OS .61 RF header question
On the Mac's website there is a page listed special application headers, scroll down and you will see the rear exhaust "fuse top" headers. They have .5", 1", 1.5" and the left hook headers listed there. (I think that OS header you got with the Hanno should be about a .5" offset).
[link=http://www.macspro.com/specialapp.asp]Mac's Special Application Headers[/link]