[jfairbank]

I have a 66 Mustang with a door data tag says it's a code A engine. PO replaced the original intake 4vv carb with a 2 vv. The intake was from a 67. I am putting it back to original. But after removing the intake and carb I found a stamp on the block and now I'm thinking this isn't the original block either. The code I found is 6A4 and then a letter or number I can't read. Looks like the top of a 'B' or the top of the number '8'. Door data tag for the date is 03M (Dec. 3, 1965). I'm guessing the block code 6A4 is for Jan. 4, 1966. Is this right? If I guessed right it isn'tthe original block....

 

[JVince]

If I remember correctly, 6A would be a '66 block. However the door tag # may be incorrect also. I have a door tag that says my engine should be a '66 I6. MY block and the rest of my car is C-code '65. PO didn't know my the door tag (and entire door) is a '66 replacement. I would check the stamp on your fender well and use that to decode your engine specs. Also, and this is just a guess: Would the block cast date have to be exactly the same as the door tag date?

 

[jfairbank]

Door data tag matches the stamp on the fender. What I've been reading the stamp on the block should be within a couple of months prior to the data stamp. My guess would be a November or October date code. So if "A" represents January then the block was built after the car was built which wouldn't make any sense.

 

[66stangFb]

I'm not an expert on this, but I'd guess this is the correct block for the car. During this period the paper work and assignment of numbers started before the build. The date on door tag is only close to the time it rolled down the line. Even the build number is not an exact build number. Three cars rolling down the line at the same time, one behind the other, would not have consecutive build numbers or the same date.

 

[jfairbank]

Hope your right, cause I really would like to keep the car as original as possible. I was lucky to find an intake that had a casting number that would be with in the time frame of the door data plate.