Not sure, I got mine from Magnum Force years ago.
Also my focus on the robustness of aftermarket front hubs for a track car, do not forget, typical 6061 alum, likely the material here, loses nearly 2/3 of its strength at only 300F, which in heavy braking conditions, is obtainable.

One aspect of the Wilwood hubs that did interest me, was the screw on with o ring cover cap, not a feature of the Dr Diff hub. The reason I liked it, I toyed with the idea of trying to oil lube the bearings instead of grease, which again IMO, would help with temp concerns. Still may try it with these new ones, but I still have a lot of unknowns.