The early glovebox attaches in a different manner. The 1947-48 (a few early 49's) have this metal band around the attachment points.
https://www.flickr.com/photos/advance-design_parts_co/14584820638/in/album-72157631868452754/
https://www.flickr.com/photos/advance-design_parts_co/14584754750/in/album-72157631868452754/