they all are the same 5 speed awd system with an electronically variable drum that is computer cotrolled, the computer can dictate anywhere from 100% rwd all the way to 50-50 front to rear through this variable drum clutch. 03's had awd lock button, while everything after it had snow mode button instead I think. both pretty much lock the awd system into 50-50 split up to about 19mph. difference is all except the 03's alsao reduce throttle input while in snow mode where 03's did not restrict the throttle in awd lock mode, otherwise there all about the same... & there is no user input, the awd system will engage whenever the computer senses slip & will always start out from a standstill in awd up to about 12mph...