This is the storage bag that the convertible top cover folds into when the top is in the down position. Ford calls this part the "Folding top dust hood container." It is made from common vinyl top material and is always black. It measures 15"x27" and the bottom portion is sometimes, tapered down to 8". The same design was used for many Ford Products of the day including Torino, Montego and others. Current offering does not have a tapered bottom, it is square. Pictures will show both styles that we have found.
Ford Part #: D0OZ-7654486.