the Ken's super close up - last 2 pics on the first page of this thread. As far as I can see the lever is quite a bit different from the Pro Lever but the caliper looks very c2-ish. But Im sure I read somewhere on the c2 blurb "developed from our first hydraulic brake- the c2 is blah blah blah"
The lever looks like the sport version. i say 'looks but it is a sport lever just the earliest.
Not knowing enough about that particular brake i cant really comment because the earliest hydraulic was a closed system and the later O2 was an open .The differences were seen on the lever reservoir top. The open system could be adjusted by turning the dial and on the closed the top was solid(just like todays brakes. However, despite zooming right in i can tell if that lever has an adjuster on it or not. If its there then its painted black and blends in to well to be seen properly.
Have you read the users guide
it has pics of the C2,Os,DH4,XC4 so you can identify it.
1976 Raleigh Chipper,1991 Muddy Fox Adventurer,1991 Claud Butler Ventoux 400 ,1992 Raleigh Diablo ,1992 Rudy Project, 1995 Cannondale M200 ,1997 Santa Cruz Tazmon ,1997 Specialized Stumpjumper ,1997 Specialized Rockhopper ,1997 Marin Quake 9.0,1998 Marin Pallisade trail ,1998 Raleigh Torus,1999 Orange Clockwork , 2005 Kona Hahanna ,2007 On-One Inbred ,2010 Orange Pure7 And of course The Ti
The Marvellous Mechanical Hope Collection ,and other Hope niceties