Vintage Susan Howard of California Dress

They don't make dresses like this anymore! Found in my Mother's closet. This vintage 70's/80's dress does not have a size label. Zipper back, long sleeves, elastic waist, ruffled V neck collar, button cuff. Split front skirt with a fly away type front. My best guess is an 8. Measurements: laying flat, 17 inches pit to pit and 28 inches waist to bottom of hem.Excellent condition. There are two string style belt loops. No belt.