Simplicity 3717 vintage sewing pattern, dated 1960.

Misses' One-Piece Dress with Detachable Overskirt and Belts:

Dress has partially scalloped neckline, raglan sleeves and left side zipper. Slim skirt has gathers at side front waistline and slit opening at lower end of center back seam . V. 1 has long sleeves with zipper at lower edge and self tie belt. V. 2 has short sleeves, self belt and overskirt with soft pleat on each side of center front waistline. Overskirt is gathered into waistband at back and side front and has back zipper. 

Size  12:

Bust  32 inches / 81 cm

Waist 25 inches / 64 cm

Hip    34 inches / 87 cm

Pattern is UNPRINTED and checked complete, EXCEPT FOR piece D, front facing piece which is MISSING. Envelope has wear and tear around top end and opening.