Orient 3900, Very Rare Item...

This is my first dress watch and i do not know the detail of this watch... :) I do believe that it was a rare item orient watch, with unique day and date position and also have a thin / slim case . Most of my friends said that it was a quartz watch and after holding the watch and looked it with detail they surprised it was an automatic watch. Bellow was the only information of the watch that i got from google 

This is an Orient 3900 caliber. The watch is usually seen as the Orient Fineness and was Orients top of the line watch in the late 60s. It is a 35j caliber and was renowned for its exceptional thinness at 3.9mm. I have not seen this variant before but my guess is that this is some kind of export version. I will make a more extensive post when the watch arrives. An interesting detail is the double day/date window, made by having a notch in the day wheel for the date. 
Source taken from:http://www.orientalwatchsite.com/forum/index.php?/topic/6485-interesting-vintage-orient/

Does anyone know detail historical of the watch? Please let me know. :)