Found this at an estate sale & thought it was adorable. The zipper & buttons are on the side. Zipper is called “regal” which I never heard before & couldn’t find any info on. It has no labels.
You may be right - I keep going back and forth, but the contoured waistband strikes me as odd for the 70s. I would expect a straight waistband, but then again, it would have been worn with a belt in the 1940s/50s so the waistband is almost irrelevant... corduroy is certainly the popular material of the 70s....