Kind of true....SF1, SF2, SF3, and RTK are on receivers.

AutoTrac is on the display. Back in the day they sold 2 levels, AutoTrac SF1 which only steered when connected to a receiver w/ SF1 signal and AutoTrac SF2 which would steer with any level GPS signal on the receiver including RTK. That's what people mistakenly call "SF2" or "SF1" on a 2630 for example. Deere has since simplified it to just one AutoTrac activation instead of the two levels and yes it's $250 to upgrade from the SF1 version to the SF2 version. If you dig in the activations screen you'll likely still see either AutoTrac SF1 or AutoTrac SF2 listed....that just means what that display will autosteer with for signal....that has nothing to do with the receiver you actually have on the machine at the time.