1968 340 Block VIN Location?

340 block, 1968 casting. Where would the VIN be stamped on this block? I looked at the pad by the oil pan rail and it is blank. Thanks in advance

1968 model year - Top rear of the flange that mates to the transmission - if it has one.

'68 castings were also used well into the 1969 model year though, by then the pad would have been stamped on (or near) the pad by the oil pan if the block was put into a car at the factory.