I couldn't seem to find any information on which years they did not use use a date code if ever or when they stopped dating the main blade tang. I figure it was probably after they stopped actually issuing them but wanted to ask, also the models which have a bail are models that were made for private purchase correct? I read and interesting article awhile back about how the military used the rivetless hole to hang from some type of launcher and used it as a way to determine i guess the angle to position the launcher, very cool read!