The hubs & stubs are 30 spline, but so are the inner shafts, and have neckdowns similar in size that stock D44 shafts have.
The axlejoints are unique to that axle (not sure the Spicer #). They are in between the size of D44 joints and D60 joints (and would probably place somewhere between them for strength as well). They do use external clips on the u-joint caps though (like on driveshafts), so you won't see the cap-spitting problems common on 44s.
Overall its stronger than the 44, but nothing close to a 35 spline D60.
That 50 could be made quite strong if someone made alloy shafts for it, but I've yet to see any TTB offerings from anyone yet myself.