Playing as the US in the campaign game I note that the E-1b Tracer is available in 1949. According to Wikipedia (the font of all knowledge) the Tracer was not in use until 1958.
Edit: I see that the Tracer is only available for research in 1949! Kindly disregard my rant...
Edit: I see that the Tracer is only available for research in 1949! Kindly disregard my rant...