Dreamgirls HELP

I am looking for pictures and information on the quick costume change Jennifer Holliday does during the "I Am Changing" number. Does anyone have good pictures of the costume. I have the seen the video on youtube but it is way to fuzzy. I am looking to design a similar costume for my high school so any help is appreciated.

"She was wearing an overcoat. At a certain moment, the stage darkened and there was only a spotlight on her face. She took the overcoat off and then the spotlight widened to reveal the costume under the overcoat"

It's not an overcoat. It might be easier to descibe the costume in reverse. Picture a person wearing a long dress and grabbing the dress by the hem and pulling it up to the neck to create a poncho type blouse. Of course it's a little more complicated than that but that's the basic formula for the costume. When Effie gets to the point to make the magic happen she unfastens the poncho/blouse and the fabric falls down to gown length and reveals the opposite side of the fabric.