I have 2 odd M1 helmet liners. I was digging in my closet to see what manufacturers they were and noticed one says US then 4W under it then M11 inside the crown. It looks as though maybe it was a reject converted into a toy? The other has post Korean webbing perhaps Vietnam but no marking at all. Did the US make liners with no markings? It has the correct webbing with nape. Please judge.