I may very well be wrong, but my suspicion is that UAW organized all (unionized) GM employees, so that there wouldn't have been members of the steelworkers' union at EMD. My ***GUESS*** then is that the "lingering effects of the steel strike" that delayed new-locomotive production at EMD after the end of the UAW strike would have been a matter of unavailability of material from subcontractors organized by the Steelworkers.
(The AFL side of the AFL-CIO was primarily made up of "trade" unions, organizing workers who did certain kinds of things wherever they worked, and the CIO of "industrial" unions, that tried to organize whole enterprises. And I think the UAW was an "industrial" union. Also, in the steam era, was primarily a metal-working (casting, riveting, welding...) and so would naturally have been organized by the Steelworkers on either strategy.)
My history is hazy, so if anyone knows more, please correct me!
Supposedly the F2 was built because EMD couldn't, immediately, produce (enough?) of the more robust generator needed for the more powerful engine used in the F3. So an F2 was basically the F3 design, downgraded by using the old-style generator from the FT. I can't remember ever having been told whether the original, 1945, F3 was built with hand-made prototypes of the new generator, or equipped with a generator which, on testing, turned out to be inadequate, or...