As far as I know, it's just the tcx with a bunch of updated parts on it. Most of those parts of which you can currently buy off the shelf.
Things you can buy currently:
-Narrow chassis
-Thicker Top deck
-Lowered Shock Towers
-3 hole steering knuckles
Things that will be new:
-Revised steering rack optimized for 3 hole knuckles
-HB's very own gear differential.
-Tiny rear steel driveshafts
-Possibly a new chassis to accommodate the new steering rack (not sure on this one)
There are probably a few things that I'm missing, but the major stuff is all able to bolt on to the old car. It's just slight refinements, not an entirely new car. Of course Hiro would know more and be able to clarify when he gets a chance.
-Korey