Purchased this in 1979. Haven't seen one like it anywhere. Curious about what
collection it was etc. Any thoughts?

 

Hi,

Might be ref. 166.0183 as seen here Purchases made through these links may earn this site a commission from the eBay Partner Networkon Ebay.
Hard to say what collection it belongs to.
is it steel or gold caseback?

 

Different lugs.

But my guess is international collection. Or a US spec case. What time period was the US cases?

 

thanks....steel case back.

 

Thanks for the thoughts. Not sure about time per. for cases. Bought new in 79 from A.D. Back has never been off, never serviced. Suppose
there might be stampings inside.
Keeps good time so not inclined to mess with it.

 

That looks like it definitely....

 

I would definitely get it serviced before using. That's like letting your car go 100k miles before changing the oil...