Was the filler standard or optional at extra cost? I couldn't find it in my lists of optional stuff but maybe some plates were located in the middle.
The filler was standard equipment. Not sure if the plate brackets were factory or dealer installed, as most front plates holders are now. The FAM does show the plate bracket, but it’s for a ‘54.
The bracket for a 47-53 AD is offset. I presume it was done that way to fit the filler panel. Look at the picture and you’ll see what I mean. I have never seen a plate mounted in the center, always offset but I have been wrong before.