As far as I know, that was the father of the L5100 (or the Omega 1045).
Omega added a few touches - mostly cosmetic as far as I know - and called it 1040.
This one and its chronometre-certified sibling 1041, used in the Speedmaster 125 (the first chronometre certified automatic chronograph, btw), were the first ones with central minute counter but they had a subdial for the 24-hr indication in a recessed subdial under the continuous second at 9 o'clock.
From the little that I know, they are considered a better movement than the L5100 (aka Omega 1045) and have fewer or maybe even no plastic parts. Maybe our more technically-versed contributors can shed some light on this?
Cheers,
Fabrizio