You will need to provide a bit more information, though it is very likely that your watch dates from the 80's. It's definitely not from the 60's. Please post a picture of the watch and please provide ALL the information that is written on the back of the watch, exactly as it is written. That will help us determine what you have and when it was built.
Look at the attached foto SDC15743.jpg. Nr28 Se M/F16 is a swedish military marking telling me it is originally from the Swedish Air Force Regiment Nr 16, Uppsala near Stockholm. The story is that this watch was distributed to flight crews that flew a plane called A32 Lansen, translated meaning attack/bomber the Lance, which flew from 1958 to the late 70´s. The wrist band is from an old Citizen watch.
A typical example of that watch might sell for US$50-US$100, but with that watch's military history it is really hard to say. Any watch, Seiko or otherwise, that is military issued and is military marked is worth SUBSTANTIALLY more. ---A
What would you estimate that substantially more is? One neat thing about the setting wheel is that you have to unscrew a couple of turns before you can pull out and set time and date and so on, its like a secure lock. Or perhaps is all the Seikos equipped with this securing?