As far as I know Juka Motorsport supplies all parts and also offers major rebuilds for both Octavia and Fabia WRC. Juka is team very close to Škoda Motorsport. When there was the highest demand they were even building S2000 cars for factory. You might know the team as a long time partner of Škoda Deutschland (for more than 10 years), now they are running S2000 car for Sepp Wiegand and Octavia WRC for Matthias Kahle.