Here's a copy of some info I provided recently on the subject:
Original 1965-67 and early 1968 units will have round tags pressed and staked into a recess in the main casting on the drivers side, at least from what I've seen here.
Below is an exert from some information on-line referencing Rochester and Carter built carburetors:
For 1967, the Rochester Monojet (1MV) and Rochester Quadrajet (4MV) carburetors had the date code, identification number, change letter, and broadcast code stamped on a round metal disk pressed into a recess on the driver's side of the main body. The date code is again in a letter/number format where the letter is the month of manufacture and the number is the year, e.g., C7.
Starting in 1968, the Rochester Monojet (1MV) identification number was roll stamped into the drivers side of the float bowl, along with the broadcast code.
The very early 68 Quadrajets (4MV) had the identification number, date code, and broadcast code stamped into the round metal disk pressed into a recess on the driver's side of the main body (like the 67 Quadrajets). Later Quadrajet carburetors were roll stamped into the vertical boss on the driver's side main body (just behind the secondary throttle shaft). The date code was stamped either on the base of the carburetor toward the rear on the driver's side of the car, or on the vertical boss next to the identification number. The date will be in a four-digit format (where the first three numbers are the Julian day and the last number being the year).
Carter-built 4MV Quadrajet carburetors will show the "MFG BY CARTER" designation and continued using the date code format where the letter is the month of manufacture and the number is the year, e.g., C8.
There is also some confusion with roll stamped SR or Service Replacement units. In 1967, for example a Quadrajet starting with 703 instead of 702 indicated CA emissions or A.I.R. was used on that engine.
In later years when they made batches of SR carburetors for the 1967 model year they were roll stamped starting with "703" instead of 702. Some literature on the subject indicates that using a "3" instead of a "2" on the later roll stamped units meant they were SR units not strictly for A.I.R or CA applications.
Doesn't really matter either way and I'm not taking sides or going to get into a pissing contest with anyone about it. I do know from what I've seen here original 1967 Quadrajets will have a round tag on the main casting vs being roll stamped.........Cliff
