i have a type 1 m1 helmet liner (detachable webbing). bought it at a military show there were 2 with the same sticker. anyways i bought it and im a bit confused with the sticker in it. some people have told me that the 73 mark is the manufacturing date and some say the 74 is the manufacture date. you can see the 2 numbers dont match up in ANY way not the month or year. i took a look at my 1967 type 2 liner which if you know your codes should have the same number style but in this case the type 2 liner numbers match saying "31MAY67 DSA-100-67-C-4525" so is the type 1 sticker a manufacturing defect?