I'm not calling your research into question Tom (im still a newbie compared to many here!), I just find it intriguing - somewhat like the 66 CB case.
Does anyone know if midcase and case back were produced as a unit? When did casebacks get stamped? When you consider that 105.003s were produce until '69, but retained the - 65 stamp, its just strange that Omega would (or even would be able to) have to the control of one straight lug reference that was squeezed in between, especially with all the other speedmaster refs they'd be producing at that time.
A puzzle for sure... great, more speedy trivia to obsess over.
馃榾