Seamaster Quartz – black dial questions

Hello – I am thinking about picking up a pre loved Seamaster quartz, black dial. It appears to be a little older, where would I find the serial number etc on it? This would be my first Omega alone side of my Breitling’s, Tudors, Seikos etc

I’ve noticed by browsing that at sometime they loved the date from 3 to 6, the one I’m looking at has it at 3, black background

Are there any items to look out for or that I should consider when purchasing? It does not have a box or paperwork – so just…

Seamaster Quartz – black dial questions