On the ET the hubs are the same, just the front changed to go trailing. The AL rear center shaft isn't part of either, but is a nice upgrade. The split center diff is only convenience, but I usually go with the full AL one for extra rigidity and the inability to strip them out when I crank down on the screws. Some people are, however, using the optional rear hubs along with the .4 ackerman and bellcranks now, and seem to like it. Those aren't part of a .3 though and are more of a tuning option.