I know it's not a Z, but my 69 SS396 born with intake is E 29 9 (May 29) for my 08D body. My born with engine was cast G 23 9 (July 23) . That's a month before my cars birthday. Aug 22, 69.
IMG_20150809_155437 Born with by
Dave H, on Flickr
20130811_100301 by
Dave H, on Flickr