Is this Omega genuine?

This Seamaster is very light weight - particularly the bracelet. It does not seem to be made out of SS. Did Omega ever use other materials in the 70's? The gold links in the middle of the bracelet are hollow but it still seems suspiciously light. It seems to me that it would be hard to fake the 1342 movement (and not worth it) but this is the first one I've owned so I have nothing to compare it to. It does function exactly like the 1342 should and it even has the common flaw - the hour hand getting stuck when the date wheel tries to advance. The serial number puts it as a 1979 model which is another reason I'm curious - its in amazing shape for a 40 year old watch. Thanks!

Looks all good to me, I don’t think it would be worth it to fake it

Thanks!