Dig this article I found. It will either help or confuse you. I looking for a way to tell if yours was a 2V or 4V motor and I still havent found that info yet. There is the link http://www.classicmustang.com/casting_numbers.htm

 

thanks. this article does help a little. I was digging more as well and came up with the code basically saying it was a fairlane block. This article explains it a little more. It may still be the original block.

 

In 1968 the difference between the 4 barrel and 2 barrel was the carb, and the 4 barrel engine had 10:1 compression as opposed to 9:1 with the 2 barrel. Those are the only differences i know of or could find. To get that 10:1 compression ratio they used flat -top pistons, Therefore all the heads are the same as well.