2002 Ford Explorer How to determine the year of an engine?

The "serial number" aka last eight characters of a VIN from the top rear of the block, right behind where the intake manifold would bolt to the block.

That is were it used to be located, I do not see any reason for relocation at all. It will tell you the model year, assembly plant, and production sequence number.

To know what year exactly they are would require the date codes. They look something like 8F20, or 8C12, etc.

I hope the 5.0L engine is the year it is said to be. If it is. Make sure to take the ECM that goes with it. The ECM is right "in" the firewall on the passengers side, it has a large wiring harness connected to it.
These 5.0L engines go a "LONG" way.
An easy 200,000 miles +.

I hope this information helped you out.
Good Luck;
Rick

You are welcome xshawx;
Usually only General Motors stamps the info on there.
Good luck with the engine if you buy it. Remember the ECM !
Good Luck;
Rick