Gilera Runner 2 stroke parts compatibility

Hi all! I've tryed to search the web but no results... What is the compatibility between Runner firts modell (1998-2003?) parts? Are the body parts/plastics/suspension the same in 50-180cc modells? What about the engine/transmission compatibility to chassis between 125-180cc? Cylinders(w/piston) between motor blocks 125-180cc? What about the compatibility of front forks between the first/second modell (2004->?)? Thanks for the info!