MIL-K-818C was published 8 June 1964. MIL-K-818D was published 5 April 1985.
There were at least 3 amendments written to MIL-K818C. Amendment 1 was published 29 September 1972. This amendment dropped the inclusion of the pin on the screwdriver blade. The change over from pin to no pin happened during 1973 production.
You can go to "U.S. military knives" and look under "Govt. knife & bayonet document reprints for sale" to order reprints of the 4 versions of the MIL-K-818 specifications.