Quick answer with out going into the garage.
The rear hub to the best of my knowledge is the same as the b4. So are most of the rear ward parts. As for the bearing sizes they are interchangeable but I dont know the exact measurement off the top of my head.
Hope that helps a little.
Original RC 10T, T4, RC8Te, Tekin RX8. Losi Ten SCTE, Slash 4x4.