This is mostly legend. The story goes they were boosted one evening from a fenced area with a locked gate. If any of the drivetrain components are around I am not aware of it. Experienced car thieves knew enough to obliterate VIN stampings.
#39 was supposedly stolen from Jack Head Chev in CA. But I recently heard it was raced since new, never registered for street use. #43 was stolen from Hauser Chev in Bethlehem PA in 1972. Was privately owned at the time. Still titled to an insurance company.