Head stamping question

[nutz4spd]

Does anyone know what these numbers mean? They're stamped on the end of both cylinder heads on my 413. They read 11565. Is it a date stamp of some kind?

 

[R413]

Maybe, What does the top pad of the block have stamped on it?

Your heads are saying 1 15 65

 

[nutz4spd]

A 413
29 2

 

[RemCharger]

Feb 29th?? 65 wouldn't be a leap year?
Maybe sand that down a bit

 

[dadsbee]

1 29 2nd shift or 11 or 12th month 29th day 2nd shift.

 

[R413]

Jan 29 2nd shift