You will find all sorts of numbers cast in various engine components. Some are actual part numbers for the casting only, some are production codes, mold identification numbers, etc. Some parts May have a number set that can have a date code extrapolated.
In order to be able to make any sort of I.d. Of the number sets, you should pick up a copy of the service manual and the parts l;ist for the vehicle and study the entire manual preface for number identification.