Help Identifying Two 340 blocks

[1968rt]

Picked up two 1973 340 blocks. I cant figure out what the identification numbers mean. Both are January 73 castings. The black motor appears to have been rebuilt at some point.

 

[dvw]

Get a better picture of the stamping on the front side of the left deck. That'll tell you as much info as you can get about what car it was in, plant, etc. Other than that they're all the same.
Doug