Air Vent Identification

[unclemiltie]

Does anyone know what this is off of? 1939? 1940? m-series? coupe-express???
I have had this for years and never have identified it. It looks to be in nice shape and I am thinking someone probably is looking for one

Thanks in advance

[5brown1]

it looks like the one on my 37 I think there would be a part number on it somewhere to find out for sure.