On the data plate, does it have an 11 digit number (example: 1111-111-1111), or maybe a 13 digit number (example: 1111-111-11-1111)? If it has an 11 digit number, then that number represents a "Federal Stock Number" or FSN. The 13 digit number represents a "National Stock Number", NSN. The military started using NSN's, as a replacement to the FSN, sometime around 1975. So if you have either one of those on the data plate, then it's most likely military issue.
