964 authentication leans heavily on factory code decoding. BillG993 (a domain expert) lays it out: X codes = Exclusive Department options on hood stickers; Y codes = bundles of X options on build sheets; Z codes = interior options; 5-digit codes are production line instructions (e.g. …
Factory option-code literacy — X / Y / Z / 5-digit production codes
Porsche 911 (964) · factory-spec