Vintage Dress?? No tag old zipper sleeveless help me with this!!

I have this dress. It has no tags. Metal zipper. Coed is the name on the zipper. Everything about this dress tells me it is old. I would guess 1970's. The fabric feels old. The pattern of the fabric looks old. The stitching, etc.. so many things tell me it's old. I am definitely not an expert in no means. It's my opinion. If you need more pictures or measurements, please ask. Measurements are under arm under arm 19 inches. Shoulder seem to hem is 36". From side to side across the band is. 20 inches.