Engine Serial Number - V6 225 from my 67

Just uncovered my Serial number on my V6 226, out of my 1967 CJ6. The number is "KNH 336", So What I have learned today searching the old posts is that this is indeed a 1967 motor the "NH" in the serial number, but the 336 would indicate this being made on December 31, 1967 given that 1967 was a leap year which it was not, so that doesn't make sense, and what does the K mean, I found D= Domestic, X= Export, and M= Military, but no info on a "K"

Did I miss a post that explains this?