Did anyone know which is the last movement design and made by Omega? When did they start to use ETA movement?

 

They started using ETA about 1984. I guess the 101x date, 102x day/date and the 104x chronographs were the last they made, although technically they were Lemania based calibers.

 

Then.... how about the 1666 and the 2600?

 

Technically, they designed that but they don't actually make it.