Levi's made in Japan 506XX repro.
1940's type I model with 'big E' red tab, selvedge denim, single front pocket, back cinch, double pleating on the frontside, and a short boxy fit. 
 
1940's Type I - No size tag but resembles a size 40
Measurements in inches:
Chest: 22"
Shoulders: 18.5"
Back length (without collar): 23"
 
 
Stitching on the bottom of the pocket has come loose a bit. And some of the stitching on the pleats has come undone.