The Holley date codes are different than what Ford used. Early model Holley carbs used either a 3 or 4 number date code. For the 3 digit code, the first digit is the year, second digit is the month with A and B being used for November and December respectively, and the third digit is the week. The four digit codes are more complicated and became the standard numbering on the Holley carbs starting in 1972. But if you have a four number code, then the first three numbers are the consecutive day of the year starting with 001 for Jan 1 and ending with 365 for December 31st. The fourth digit would be the year.