“D” code 340 in 69’ Cuda?

That’s kinda where my line of thinking was. I guess I should just be grateful it’s a 340 like what was originally envisioned. Thank you for your input on this as there is no secondary engine I.D to be found on this block, not near the bell housing nor the oil pan rail.
May be a service replacement engine.
Replaced under warrant by a dealer?
Just spit balling