It would be interesting to know what the OEM fitment was on the those later model BDR axles. They look like Audi Quattro fronts. No tone rings and overall size.
https://www.ecstuning.com/b-feq-part...n0407271e~feq/
Hopefully DSS can narrow that down, as BDR has never divulged the fitment on the later axles, just that the early cars use E36 axles which are a direct bolt-up.
Also I'd ask DSS if the failure is contributed to the necked down areas of the axles as they pass thru the boots. (Beefed up center section transmitting the load to the ends).
The only other Achilles issue on the later BDRs is the Integral rear hub. Instead of a E36 hub with a bolted on pin drive adapter they made their own One-piece Hub/pin drive assy. If you look at the pics in the thread below, the splines end at the outer hub. The twisting torque is being transmitted to the bearing area of the hub and not the outer portion where all the shear load is. There have been instances where they shear off. Luckily the brake has kept them from exiting the fender well on the ones I've seen.
Broken pin-drive hub
But BDR evidently has corrected that issue on the latest revision. I don't know the Build # it started at. (Change is mentioned in the next to last post in the thread.)