We just bought a 2001 f250 and it has the shift on the fly. I was debating w/a friend on how it works. He says you don't have to lock the hubs for the 4wheel drive to work. i.e. auto . Now is there some sort of electric, vacuum, or hydraulic line that actuates the hubs that I don't see? if there isn't then wouldn't you have to lock the hubs like your regular front axle? Sorry for the newbie type question but I am to super dutys.