Although I'm a waffle iron nut, I'm not a Griswold expert.
I don't see any listing of this item in the blue book or red book.
However, the books do show a sandwich grill (page 195 in bb; page 175 in rb) that is of a very similar build quality. The date on that sandwich press is circa 1930's so I would probably date this waffle iron to be the same. Definitely aluminum.