I am diggin this thread. nice research and pic's. not sure anyone answered, but you had posted a question about the stitching at the bottom of the jacket, as your picture show's these jacket's had "dual" flap's with button's (you can see the button's at the corner's) to hold them open, the weird stitching is where the outer jacket "flap" would fold over flat to the jacket in the buttoned position. the same with the other side. 