ZL 1 Aluminum Block Question

[3946052]

What does the the (KPT CST) code verify?
I have noticed the 3946052 blocks at swap
meets throughout the years and was always
curious about them.
I also noticed that even though the casting
#3946052 was on the rear of the block they
had freeze plugs installed where the screw
allen plugs should be externally. Internally
there were allen plugs in the valley area.
Also the "Winters" foundry "snowflake" was
absent from the front of the blocks along with the
missing engine code or VIN on the front pad. Best that
I can recall the blocks had not been decked.
Is there a location on the the block for date codes?

Lastly, what are the avereage $$ these blocks are worth?


Thanks, just trying to better my education
about the aluminum ZL1 wonder.

[3946052]

Is there anybody that can help?
How about a reference book or article?

Thanks