how can I id year for my 2.2EJ using engine number on block?

[bbott68]

I have a '87 Westfalia with a fresh Subaru engine conversion. How does one go bout identifying the year of a Subaru 2.2L SOHC EJ engine with the engine number 164005, located on the top of the engine block. Looking toward the front of the Vanagon, the number is almost below the throttle mechanism, on the engine's top  left side (in a Vanagon, the front of the engine faces the rear of the Vanagon).  Thanks for reading this, BBOTT68