chassis, chassis brace, ring and pinions, spur, center diff mount, radio tray, shocks, center drive shafts are all different.
i had both, still have the X2 truggy with 6 races on it for sale. but you can convert the X1 tp an X2 pretty cheap threw ebay. if you get the chassis, you will have to get chassis braces, center drive shafts and radio tray. but IMO the most important thing is the new gearing
and shocks!!