What did the "F" in F Troop stand for?

I don't think they ever said . The Army is divided up into groups that call themselves "A Company" OR "E Company" . I always thought the name "F Troop" was along that line .

I interviewed the late director Charles R. Rondeau via phone in 1989, who directed the pilot and numerous first season episodes. According to Mr. Rondeau the letter F was a way to both correctly label the troop as you mention, but he also said that the "F" was an in-joke among the writers as standing for exactly what you would guess.

These are, after all, the same guys who cleaned up the old vaudeville joke on how the Hekawi got their name for prime time, and named Agarn's cousin Lucky Pierre. :)

In Massachusetts we have a State Police Troop F (recently charged with corruption LOL)

I always thought it had roots in the 4 F recruit designation (unfit for military service)