I got this at a NAWCC mart.I would like to get more info on it.I think it's a first Gereration becouse it has a none screw down crown it's set up like a early Omega 300 seamaster with a O-ring in the crown and when you pull up to change the time and push the crown back down it locks the crown.It has a none hack,none quick set date movement.On the case back cover is the brass raft wish that was in better shape and it has this number on it 5133513.The crown also a eterna marked.I know the bezel insert is wrong.The dial has the rarer marked dial with Super-Kontiki in one line I seen it at a few other forums.And when was the first year they made these 1958?And I read some thing on the net that you could date these with the number on the case.And thanks for any help.