My Zetec engine has the month & year cast into both the head and block.
This is consitent with the engine number on the donor cars Vin number & V5C, also Burton powers production date list.
That said, I would not risk that my local IVA station would accept this as proof of the engines age.
As far as I am aware, if the tester is unsure of the date of manufacture, the car will be tested to the stricter emissions criteria
