Stamping on 340 in 72 Duster?

[Divenut]

Hey folks,

Chasing threads and cleaning everything up for the new heads. Happened to notice this stamping on the block. Any ideas what, if any, significance it has? Don't know much about the motor other than it was rebuilt at some point in it's life. Thanks in advance!

 

[cudamark]

That looks like head gasket residue. Is that actually stamped into the block? The number and letter look backwards. I don't remember ever seeing any stamps that would do that.

 

[Divenut]

That looks like head gasket residue. Is that actually stamped into the block? They look backwards.

Boom! Thanks! Clear as day!