The geardiff housing is super compact and light already. For the new diff the small and large gears inside are made from a very durable and smooth composite, and the alu axles ar replaced by a composite X-shape axle . The steel drivecups are replaced by hard-coated alumnium ones. The result is less rotating mass and smoother diff action.
401593 Outdrive alu for geardiff V2 composite (2)
401594 Diff gear 10T+18T for geardiff V2 composite (4+2)
401595 Geardiff x-shaft for geardiff V2 composite
The sintered gears and still be used in the diff-case, and some drivers also combine alu and composite gears for different gear-diff feel/ action
New gears for Ery 411 geardiff (10/23/2016)

401592 Geardiff V3 composite
401594 Diff gear 10T+18T for geardiff V3 composite (4+2
The Eryx 411 geardiff has been improved with new shaped composite gears to make the whole differential feel smoother. The changes to the tooth profile are only small, but make a big difference as you will notice instantly.
This same geardiff is standard in the Project 4X car too and the new gears were in the kit since the start.