Mark in Paris[Purist]
10488
5800
As mentionned, it was indeed produced at the same time as the beginning of the 5711.
It is an automatic movement (330 S C, whereas 324 S C in the 5711), visible through the see-through caseback and measuring 38.4 mm (40 mm for the 5711).
It kept the 2 parts case design (the 5711 is 3 parts now as you know).
I mentionned it after the 5711's section in my Nautilus 40th anniversary post at the beginning of the year here:
www.watchprosite.com
A very nice alternative imho.
Cheers, Mark

5800/1A