1939 1940 1941 firewall wiring kidney shaped cover

[40larry]

Here are three different firewall wiring covers. The one on left is the commonly seen 1939-1940 cover. I believe the center picture is the 1941 cover with the wide openings for harness. The one on right has a flat top and i believe it is an early part for 1939. Has anyone seen one of these flat top covers or know anything about it? All three have identical positions for screws. Does anyone