Here is a picture of the 54' 4-speed cover, if modified with a torch it was most likely a 3-speed version without any holes. You can see how the original is raised to clear the 4-speed transmission.
https://www.flickr.com/photos/advance-design_parts_co/12243351925/in/set-72157631868452754
https://www.flickr.com/photos/advance-design_parts_co/12243537173/in/set-72157631868452754