Hi Les. I was just studying that photo! Here it is a bit bigger.
The obvious "extra" is a non-TTR frame! Other obvious bits are the upside down Kayaba forks, a different shock and reservoir, a very special complete exhaust system with the header pipe going through where the starter motor would have been, and maybe a side panel and rear mudguard from a WR. Also, does the swingarm look longer to you? Maybe the end sections with wheel adjusters from a WR swingarm have replaced the TTR snails?
What have I missed?
Is there a magazine or online article explaining the build does anyone know?