Looking for model ID help

Hello.... I'm new to this forum and have tried to look here and online for help identifying this old VC wristwatch.  Was passed down from two previous generations, however this watch has rarely been worn.  Has been stored in a box for the last 40-50 years.  No scratches at all.  Interesting looking lugs and unusual curved crystal (does not appear to be synthetic).  There are a couple of miniscule stamps/hallmarks which I cannot make out.  The band is marked 18k.  Keeps perfect time.  I have not had the case opened, nor have I been able to find a photo of this watch anywhere after googling for days... anyone out there have any knowledge to help learn more about it?  

10/03/2016 - 20:42
10/04/2016 - 06:21
10/04/2016 - 11:52
10/04/2016 - 13:07
Ref 4166
10/04/2016 - 06:21

So cool, I have one of these!

Caliber 435
10/04/2016 - 11:52

Using Dean's reference number, I found that the movement is Vacheron Constantin 435. Here's a picture of it:

 

Re: Caliber 435
10/04/2016 - 13:07

Thank you both... very helpful.  You folks really know your stuff!!.  

Nice piece to wear even today
10/04/2016 - 18:29

Although the case measurements might seem small, those bodacious lugs give it a nice presence on the wrist.