Originally Posted by Microwave

This is by and large true. In the old days there were route/aircraft combinations where both F and J were sold as F, but I think those days are gone. For some reason I've got mid-con 762s in my head for those, maybe I'm losing my mind though... In any event, I'm 99% sure that all of the current 3-class aircraft operate with F as F and J as Y when they are running non-JFK<>LAX/SFO or LAX<>MIA.