I have a Rochester Q-Jet with the 1971 Stage 1 number 7041242 on it and a date of 1509 MD. I understand that the 1509 is the 150th day of 1969 or May 30, 1969. Can I get a confirmation on this. Also what does the MD mean? If this date is correct why would a 1971 Stage 1 carb have a date of 1969? Thanks for your imput.