There is no articles or tests that I know of to prove a strength comparison. But you can apply some basic physics to understand
Why one axle would have a higher torque rating than another.
Think of your torque wrench when you tighten a bolt. The further away your hand is from the bolt, the more mechanical leverage you have. Now apply this to your pinion gear teeth. The larger in diameter the ring gear is, then the further away from the differential
Centreline you can place the pinion gear. The further away the pinion gear is away from the centreline, the more leverage the gear has to try and turn your wheels. If your pinion gear has an easier time turning your wheels, the less likely it is to break.
Now those gears also need to stay in perfectly aligned mesh to have maximum gear life and avoid breakage. This requires stiffness
In the gear housing. Flex allows the gears to become misaligned.
When a banjo a banjo axle is loaded hard, the ring gear tries to get away from the pinion. When it does this it loads and flexes the axle differential caps. Particularly the drivers side.
Because a Salibury design axle traps the differential bearings against the cast iron case, the axle caps flex much less and are able to keep the ring gear more firmly aligned with the pinion gear.
So ring gear diameter and stiffness of the differential case make the
Dana very strong.
The aftermarket has beefed up the Ford to the point that it has the best of both worlds. Easy to service, and strong enough for extreme performance, but it is still not as strong as the Dana because of the banjo design and the 9 inch ring gear. But the aftermarket has increased the diameter of the Ford to gain strength. But there is a major cost to get to that performance level, which the Dana always had. IMHO.
