I just got this at the last mart proberly paid to much for it but it's mine now.This is a First Generation so it was one of the first model's of this watch.It has a none screw down crown has a O-ring in the crown.Has a none hack none quick set date auto movement.Has original case,crown with eterna logo,dial,hands.The bezel insert a replacement.Has the brass raft on the back cover.I know the later generations had a screw down crown.Any one know how to date these I know they started making these in 1958.I would like to find out if it's a 1958 model that's the year I was born.Here is a photo of it.Does any one know if a vintage Omega seamaster 300 crystal would work in this case same style case and maybe the same size.I see the replacement crystal on flea bay for those.My crystal is a little beat up.

Great watch!
The 1958 model was very different, not a Super, and the back is engraved with the raft, not a gold medallion. I think they changed the case back in 1960 or so, but am not certain.
Here's my '58:












I don't know when the Super came out, but I think it was in the late 60s? I know the Kontiki 20 ( 20 year anniversary of the voyage?) is 1968, I have a ladies:





If your band is original, it should have a date code stamped into it:



I've always found it interesting that Eterna released the Kontiki ~10 years after the voyage.

Ah, I see your bracelet is a replacement.
Interestingly the ladies 20 I have has a screw-crown!

Hi Scott Nice watch.Here is some info I got off MWR forum on the generation one.
http://www.mwrforum.net/forums/showthread.php?t=33306
I also found out I have a replacement bracelet.I might put a tropic rubber strap on it I just ordered it.Looks like the 1958 model has the same crown set up as mine.