For those that don't know, the main difference is that the WO shafts use a reversed cup design like the origional B4. (the cup is on the driveshaft, not on the stub axle)
I thought it was better to have the cup on the stub shaft as that is the way most cars seem to be going and why the B4.1 has them now but tamiya must think it makes no difference and gives more room to have a bigger cup to give a wider angle drive.
Wonder why the 502 doesn't have them.
WO:
Normal:
