Welcome to Ford Barn. I know that you didn't ask this question, but all Australian assembled 1946 to 1948 Mercurys came from the Ford Factory with Ford rear bumpers and over riders/bumper guards like the example pictured above.
Why Ford Australia did this is a mystery. The front over riders/bumper guards are also off the 46 Ford. Even the 1948 Ford got the carry-over old style 1946 Ford over riders/bumper guards?