This piece is from (I believe) February of 1970. Its keeping time, but could probably use a service and a new crystal (the current one has a couple of scratches).
These are getting rarer to find and a similar model was just featured on Hodinkee. These vintage Seiko models will keep going up in value. The item "Vintage Seiko World Time GMT 6117-6400 Date Stainless Steel Automatic Watch" is in sale since Monday, September 14, 2020. This item is in the category "Jewelry & Watches\Watches, Parts & Accessories\Watches\Wristwatches". The seller is "watchguitar482" and is located in New York, New York. This item can be shipped to United States.