Head casting dates?

[motorcitykid]

Are there head casting dates on heads such as the 643? I bought a set with an intake from a 50,000 mile 96 Z28 and am not sure what the 4 digit code on each piece means. One head is cast 6043. The other is 6047 and the intake is 6045. I have never owned anything but cast iron 320 heads so this is different to me. Thanks for any help that can be provided.

[SSlowBoat]

Codes are inside heads toward front or rear. Will say 643 5xx or 347 or whatever after some zeros

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[motorcitykid]

Ok this what I found. The 8 digit casting number of 10207643 and the same numbers I listed in the original post. Each head has 6061 and 6061A stamped in the ends of each head on the outside (my guess is that is the material grade). I also found a 3 digit stamped number on the outside end of each head. One has 604 and the other has 715. My heads have no other numbers cast into them other than a number 4 cast into the underside in the coolant passage on one head that is legible. The casting date is not such a big deal, I just wanted to know when they were cast, mid 95-July or later in 95 or in the 1st 6 months of 96. Not a deal breaker either way. I bought these heads and intake for $150 with cam, lifters, throttle body, rockers and various other parts.