Hi, I'm searching Swiss watch (Omega, Eterna, Longiness maybe...) from a year 1968 for my brother as a gift as he is turning 50 next year. Early bird one might say but I thought that finding a nice one for reasonable price might not be so easy.

Well anyhow on my crusade I came across with this nice Eterna Matic. Seller says that reference number is 4366121. Can anyone say from what year is it? I found this one list of Eterna numbers but it doesn't match...

How to check year of this Eterna-Matic?