Not a big conspiracy theory, but I heard back in the 70's, there was a “gentleman’s agreement” between GM and Ford concerning their trucks. They colluded (isn’t the the buzz word these days?) together and agreed that Ford could have the long “Supercab” pickup market to themselves, while GM could keep the Suburban market to themselves. I think the Crew Cabs were fair game for each though. Of course, that fell apart in the late 80s if I remember correctly.

1974 Ford Supercab