Yep, made by McLeod Clutches in Texas, USA
The first couple minutes of this link will show you how these work and fully adjustable
http://www.youtube.com/watch?v=LW_QHZM0qN8
Possibly source ex-Ebay?
Or from the manufacturer, these can be had with or without the master cylinder
http://www.mcleodracing.com/categories/Hydraulics.mcl
Lots of discussion on USA forums as this is a fairly common setup, LS-1 Forums, Corvette, etc.
GW