The best way to tell is years of historic research...
ECL(exception) codes are different for different options, this is due to the overall car configuration (reason could be account for the parts used for a particular option? ~ inventory control?) even when one would believe there should be no bearing on one another.
An early car and a late car configured the same EXACT way on an order form could and most likely will have a different ECL code for some of the same options when illustrated on the Factory Generated Window Sticker.
Some things become a required add for an option, some become included in option, some get broken out from an option, some are no longer available with an option.