is a realistic possibility. The people who answered your questions are likely low-level customer service "grunts" who have no real knowledge of and access to vintage model information [catalogs, technical manuals, etc.]. How much "research" were they able/willing to do to answer your questions - especially considering the answer was not likely to bring them any new revenue??!
Personally, I think you're more likely to get the "true" answer by questioning a collector forum [if you can find one with specialists in this brand] than by emailing a general "customer service" address in a watch company.
Unfortunately, I personally have no answer for your question...
Maybe the Military Watch Forum has some folks w/ knowledge in this area?? Good luck!!
The Patron Saint of Seiko Collectors