On your engine block cast date code D1057.
Is there 4 digits or 3 ?
What is interesting is your engine block was cast,
D 10 7
April 10, 1957
and 5 days later it was stamped
T415A
April 15, 1957
You could say it took GM 5 days to cast and assemble your engine.
It is common to see the letter i (eye) used for the number 1 (one).
Factory worker must of only been issued the letter i (eye) die stamp.
