Well it all depends on how many chassis's you want? like for e.g i have a VW bora in my slrr & it comes with a racing chassis & a normal chassis & the other i cant remember but it's been scripted etc to have 3 different chassis but share the same catalog of parts where as for e.g my ford boss 429 only come's with one chassis so basicley it depends on how many types of the chassis you want weather it be 1,2,3 or 4? all depends on what car is made but they dont need to be scripted into the cars.rpk either that we'd all be fucked