For the Y blocks, I’ve only recently started recording the side of the block in which the casting number is located on as I sonic test them. Even when the numbers are similar (ie. EDB), I do find that they can be found on one side of the block or the other. There doesn't seem to be a set rule for which side of the block the casting number can be located on. The same seems to hold true for the block date codes.

The casting numbers do a fair job in identifying the cubic inch displacement but even those can be misleading. ECZ blocks are a good example. While most are 312’s, there are still some ECZ 292 blocks out there. The ECG blocks seem to be pretty much confined to being 272’s while ECK and EDB blocks are 292’s most of the time.