I didn't answer my own question. Shafts don't really break while towing. Saying that things are better because they are in a 3/4 ton is exactly the kind of argument I was trying to avoid with this thread: back your info up with some kind of logic, not just "it has to be stronger because 3/4 is bigger than 1/2. Again, the 60 is definitely stronger in every way except shafts. I am arguing shafts alone. Pookster, your argument is wrong (if I understand it correctly). When you say the weight has to go somewhere, you are right of course. That weight creates a shear stress on the axle. It would take roughly a 80,000 lb. load to shear a shaft of that size (assuming 60,000 psi for steel), and assuming that load is not exceeded (it won't be), that shear stress is not relevant to the torque load the shaft can take. That's right, that shear stress has absolutely NO impact on the torque load the shaft can take. Period, that is how it works. Now, it has been said (and I agree) that there are some forces that do make SF axles weaker (such as bending caused by the lever arm from the diff to wheel bearing and the wheel bearing to the wheel). SF is a worse design in pretty much every aspect, but I am still not convinced that their max torque load is really hurt that much by being SF.
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