I know some Admirals from the 70s could have the 6551 calibre without any special marking on the dial, but I was under the impression that all 431 equipped watches were marked Ultra Chron.

Here is an Admiral (typical 70s case, came with many movements throughout the 70s, from Longines own to Record, ETA, etc) that is claimed to contain the 431. No movement shots provided in the listing. Assuming seller is not lying about what's inside, could this be legit or franken?

 

Plenty of Admirals have the 431 movement, but I've never seen one with 'Automatic' written in the same typeface as the early Conquests like the one you show here. Usually the word will be printed in a more utilitarian font.

The other alternative is that it has a 341 movement, which is more in line with the typeface on the dial.

 

Thanks for the comment. I asked for a mov't photo, so we'll see what comes out

 

if its the right movment what clean watch

 

It got sold (not to me). Never got any reply to my movement question so I hesitated.

 

Ohh too late...I have the exact same watch, with same dial layout. There is a 431 inside as well.
EDIT: mine is without lume though

 

Ah well, one cannot win them all! Thanks for the post