68 casting 440 with S 440 in ID pad, vin pad is blank, cast date 9-27-68. Why the S 440 on ID pad?
That looks like a 9 not an 8. S is a service replacement as stated , either over the counter or warranty , a warranty replacement SHOULD have been stamped by the mechanic installing it . Service replacements should have a tag that was affixed by a rivet giving a code as to what spec the engine was built to.
Look at the 9 for the month and compare it to the 68, you can then see that it's an 8, looks like a V on upper right corner.
I see it now , you are correct.
That aside Chrysler had horrible inventory control, that was either lost in the shuffle or it had an issue that caused it to be cast aside and fixed at at a later date, when the block was cast doesn't matter.
Do you have the engine in your possession ?