I'll have to get my signature changed.
Car was built December 17, 1966 per Marti.
Thanks don't know what the difference is other than the markings on these intakes. Really never studied them that close or had the reason to.
Since we don't have the assembly date for your engine or from most of the examples guess we're going to have to settle, at this time, for the cars build date.
Looking through my pictures of S codes from your car's production period the finds are not nice, cut and dry IMHO. Will try and organize them and my thoughts and post some information for you tomorrow for your to evaluate