Various '70s Design Signature
In the seventies, Seiko had came out with a lot of funky designs on their wide ranges of watches. When we look at the vintage watches nowadays, we could identify these '70s watches by a few characteristics. Not always right, but that's not far out.
One typical clue, is their dial. The have brought out many dials with colors not been used before. Blue, green, red, yellow, and I had seen a few even with mixed colors that changes while you look at different angles.
Another characteristic is the dial markers. They loved to use raised three dimensional ones, to make the look of the dial very profound.
Day/Date position. Typically, they are located in the 3 o'clock position. In this decade, they had some having the window opened at the 6 o'clock, just like the 6116 shown above. I do have a few with the same characteristic, on both automatic and quartz models.
If you had looked at these vintage for quite some time, you could also notice the funky design they had on the case style and the bracelet. Shapes of different kinds like in oval, hexagon, octagon, perfect square, and also at least one in irregular shape. Integrated bracelet is also one typical sign. Like the 6119 here, the lug is totally different from other typical watches, and the bracelet endlinks are designed for this particular watch as well, no alternative.
Many had said in terms of design, the '70s is a big decade where almost all manufactures had some really iconic, great, or even weird designs, where they were brave enough to bring this out to the market without too much of a concern in acceptance. Seventies, really rocks!