Where all EJ20G engines closed deck? Also which years and models were these engines used?

Thanks

 

No I dont think all were closed deck.
I think you can idenify them by some hatchings under the crank sensor.
mine has mine is a 93 wrx saloon.

 

No only early ones and later Type RA blocks up to version 2. Apparently some have the oil spray jets and some don't. The crosshatching above the oil cooler and on the bellhousing is what identifies them from the outside.