The Seiko 6139 automatic chronograph – a historical movement in its own right, like this quite rare and full-serviced 1972 Seiko 6139-6032 "FORWARD Coke" chronograph here, on its original Seiko SpeedTimer bracelet and with SpeedTimer boxes and instructions manual – was one of the first automatic chronographs created and ranks with Zenith’s El Primero and Heuer’s Calibre 11.
 
Why do we call this Seiko 6139 not only rare, but also an “Isuzu FORWARD Coke” chronograph? 
 
Per our research, we assess Seiko worked with Japan-based Isuzu Motor Corporation to release a rather limited edition of the Seiko 6139, the Isuzu FORWARD Coke, in early 1970s. Easily one of the rarest Seiko 6139’s (more so than even the legendary Seiko 6139 “Teal Sunrise”), information on this watch is scant, almost certainly due to a limited dial production run. What negligeable information we initially discovered pointed towards this Seiko 6139 being jointly issued with Isuzu.
 
We did a research “deep dive” on the Isuzu connection, and assess Seiko issued this 6139-6032 with Isuzu to commemorate the success of the Isuzu FORWARD (otherwise known as the Isuzu F-Series). Although Isuzu has used different “FORWARD” nomenclature fonts on its F-Series trucks over the decades since its 1970 debut, our research revealed the font the Japanese company used in the early 1970s and 1980s was quite similar to that used on the Seiko 6139 dial.
 
The Isuzu FORWARD is an enormously successful line of medium and heavy-duty commercial trucks manufactured by Isuzu beginning in 1970. Although not to be confused with the GMC-badged Isuzu light commercial trucks sold in the U.S., the GMC variant light truck also uses the same FORWARD name and similar font as the Isuzu F-Series.
 
We strongly assess the watches were given as an award possibly to key senior Isuzu employees involved in the development of the Isuzu FORWARD line – if Isuzu had the dials produced by Seiko for more mainstream marketing and promotional purposes, we would expect a much higher number produced for general public consumption.
 
Isuzu continues to produce the F-series to this day, and the truck is available in 2WD and 4WD, in addition to a variety of cab styles and engines; the truck is also used by the Japan Ground Self-Defense Force for rear line duties, to include supply and logistics. Likely related, this would not be the first time Isuzu had provided a Seiko to its employees – in the 1960s, the Japanese company awarded King Seiko 44-9990 Chronometer-rated watches to loyal employees.
 
But back to the Seiko 6139 automatic movement itself – in the late 1960's, Heuer and Zenith had taken hold of the entire sports watch industry by racing to become the first to produce an automatic chronograph.  It has been widely debated who won, but in the background of this skirmish, Seiko quietly created their own at the same time, beating the Swiss at their own game – the Seiko Ref. 6139.
 
During the early months of 1969, Seiko put the final touches on its revolutionary 6139 chronograph - in fact, the Japanese company first began putting the 6139 in automatic chronographs as early as January of the same year.
 
Seiko published its first advertisement for their new automatic 6139 chronograph in February 1969, easily beating the Swiss – however, the company was concentrating on the release of the world's first quartz watch, the Astron, which would completely disrupt the watch world as it was known at the time (again, much to the chagrin of the Swiss watch industry, we're certain).  We possess 6139 dials dating back to October 1968, indicating Seiko beat all other rivals to produce the world's first automatic chronograph.  Period.
 
The Seiko 6139 was the first chronograph to have a vertical clutch, a feature considered to be one of the hallmarks of a superior automatic chronograph movement.  The 6139 features an automatic column wheel timing control and an integrated chronograph, which means the entire movement was designed and built to be a chronograph, vice being an automatic movement with a mere timing module.  It also features a single register chronograph allowing time to be measured in increments of 30 minutes.
 
This Japanese Domestic Market (JDM)-only Seiko 6139 comes on its original stainless-steel Seiko SpeedTimer bracelet, and with a nylon strap, rugged travel case, and springbar tool.