Is this a variation of the Mariner III?

My understanding is the Mariner III is ref. 396.0986, cal. 1430. I believe there were several dial variations as shown below:


(pic by member Michael Ettridge)

Here are a few more pics of the most common Mariner III:


(Pic by member ANALOGUE)

But what about the model below (cal. 1420)?
Is it a Mariner III?
Any idea what the reference number is?

Careful examination shows the case is slightly different from the 396.0986, cal. 1430 above...



This shot might show the case difference more clearly:



I believe there can be dial differences within the same ref (e.g. the addition of the “QUARTZ” text under “Seamaster”; the double striped border on the glass...), but it’s the case and calibre differences which make me wonder what this one is...

Any ideas?

Thanks!