Couple of 69Z Questions

[TimG]

I'm not real familiar with 1969 Z28 stamps, but I'm pretty well versed in stamps in general. My data shows that they had gangs set up for each engine option for the day they stamped. You can't compare a 1967 June 3 built IL stamp to a 1967 June 3 JE stamp.
That being said, both V0107DZ stamps should be similar or identical. I wouldn't think they had two stamps set up.
I've seen some exceptions where they stamp the date only and return later to stamp the assembly letters, but you can tell as the letters are uneven.