Mine uses kdx400 cases the same they used on the works bikes also i have the same stroker crank that was used by the works teams. The bike in the uk is the same set up as mine i have spoke to him some time ago when he was building it darrens uses a kdx450 motor in his with a kx500 piston the woeks bike that was used by dave thorp was 398cc when he was about 16 years old they started to use 443cc in the uni trak bikes in 1979