were z11 cars built early on for the event? The later cars could have been part of Z11 fever. guys liked them, then ordered them for a while promotional deal.
Could this be one of those cars, maybe a special person owned it? just referencing the 612 number, though was close via date code. Was the 396 a later idea or did this start from the first one built?
This is a very nicely done restoration and is worth what they are asking. Unfortunately for the seller, they better have some documentation or they won't get the 75k.