date codes???

How does one read a casting #?

I have the flywheel in NY and the short block in Scottsdale, just curious which 280z I have?

It appear to be a date code on the flywheel, 225 mm and says E-30, which means little, I think.

Date code would tell me if I have the good block. I think the pistons were flat top, but date code should confirm this.

An E-31 head that I have, seemed to have a 5/69 code on the front.

Confused?

Rick