Maybe I'm missing something in the STCS, but I'm not sure what "is" a chassis? Is it seperated by vehicle style, sedan/coupe/convertible/roadster? Or would it correspond to GM's x-body/j-body/f-body ect.

Why ask this question: well what if a chassis was built from 1992 to 2002 but one varient of that chassis (say a sedan built from 1996-1998) had access to say a throttle body. Would all the other varients (say a coupe built in 2000) have access to that throttle body?