[Als 70 L78 Nova]

I was looking at buying a 1970 L78 Block. 3969854. It is a CE block and has no casting date but does have the two screws. Factory mistake I imagine. I was told that down by the starter that all Tonawanda assembled blocks were also stamped when the short block was put together. i.e. T099 or Tonawanda, September 9, 1969. Can anyone here enlighten me on this information as I have never heard of this before.
Thanks,
Al in Maine