Altec 806A Variants?

I have 3 different 806A 16 om drivers. What are any key differences between them if anything. I understand diaphragms may be different, but how much between them? I need a pair to put in use.
Attachment 85343
Attachment 85344
Attachment 85345
Attachment 85346

Hello,
All 806A, so all use the same dia.
And maybe all of them sound the same but otherwise, keep the best, the differences are the color of the painting and the year of production
I have had many over the years, excellent drivers.