The 168.0056 is the case reference number as gatorcpa has shown you above. The serial number is 36,151,424 which dates the movement to 1973.
Sorry about that - I have to remember to speak English to new members. Omega used a series of calibers (mechanisms as you call them) designated with 55x (no date) or 56x (date) from 1960 until around 1972. When they switched to calibers like yours, there was a transition period of a year or two. The writing on the dial switched positions, but for a while you couldn't tell for sure if the watch has a 56x series or a 101x series inside just by the dial. There were some other tips, but not necessary to go into here.
Desmond (member mondodec) has a great blog that's considered required reading:
http://omega-constellation-collectors.blogspot.comClick to expand...