Looks like there's a forging line around the trigger that's not found on the EA cast receivers. And the selector stops on the EA I had, and the one John posted, were cones instead of the half machined oblongs on that one. Also, EA receivers were always "J-15" as model, and "EA" only appeared as a serial number prefix.
My best scientific wild assed guess would be an early Eagle Arms. Those did have an "EA" model #.