For those actually assigned in Vietnam to MACVSOG and/or the 1st or 5th Special Forces Groups, it was widely known that
their preferences were Rolex SS references: particularly the 5512-5513-1680 Submariners and GMT models.
Many SF personnel were already SCUBA qualified. An unmarked Rolex was sterile for purposes of
cross-border operations conducted by CCN or other SOG entities. The reality of preferences was known by those in the units.
Members did not skimp on watch reliability or quality.
I carried a KAR 15, 1911 Colt, Randall knife-5 shot Smith-grenades and a 1680 Rolex red Submariner. As
the Filson Company in Seattle advertises: "Might as well have the Best". And of course, a 70 pound rucksack full
of a bag of tricks and canteens carried separately.
If given the same choice again, it would be the same watch. It has lasted 49 years.