Tom,
The 120 has been discontinued for several years but I believe Cabela's (or perhaps Bass Pro Shops) sold a special project 120 sometime in the last two or three years. If that is the case, the stamp may (underline "may") have been stamped without a year mark. I suppose it could have even had Custom stamp.
Also, the first Klinkhamer project knives with smooth stag and cherry handles were stamped BUCK / anvil / CUSTOM / U.S.A. Harold is about to introduce his second series with desert ironwood and stag and I expect they will be stamped like the first series. By the way, these are gorgeous knives. He offers a set with every 100 series fixed blade and they come serialized
(1 - 100). The knives are issued at a rate of approximately one every 45 days and even the 122/124 is included. The 121 has a scaler on the spine and the 105 is partially serrated. As nice as the first set is, I find the second set to be even more desireable.