eames shell emboss / logo-glossary??  

My guess
My guess is that Vitra is correct. In the US Herman Miller contracted the shells out to various companies at various times - there are almost always makers marks secondary to the embossed HM logo. To my knowledge nobody has compiled that information definitively. I'm not sure if Vitra did the same sort of outsourcing - are there any other marks besides the V?

actually there are no other mar
actually there are no other marks. I found that a little strange as most shells of that time I saw here in Germany have the Miller-Logo.
I made a photo, have a look at it:

Can you get
Can you get a shot of the shockmounts? I dont know if that will tell me anything, but it may help.
As I just explained in another thread - there were often times in production, especially early on, when no marks were present and they relied on the paper labels.
Your chair is definitely a European production - there is a slight difference in the way the back rises from the arms. It might have been an outsource manufacturer logo.

I do have to get new screws...
I do have to get new screws for this one!
notice the small Miller-Logo:

'V' is for Vitra as far as I...
'V' is for Vitra as far as I know... .
Like Lucifersum says, the shape is somewhat different as well. If you would compare a HM shell besides a Vitra shell, you would notice that the Vitra shell is slightly more narrow and the arm rests are thinner too.

So Odd!
I've never seen the little M logo on the shockmounts before! I'm sorry, but I'm at a loss.