Hyena,
The strength issue I'm concerned with is not in the 35 spline axles and spider gears. It's in the differntial's bearing support design, and the amount of tooth engagement of the ring and pinion gears themselves. The 9" has a larger pinion gear than the Dana 70, and the pinion shaft itself is larger than the Dana 60. It has nearly double the tooth contact of the Dana 70. The 9" ring gear has a thicker toe to heel (tooth engagement) than the Dana 70, not to mention it's also thicker than the Dana 70 and Dana 60. It's more rigid, and has less gear deflection under high loads. For size and weight (not counting the Dana 70's thicker full floating 35 spline axle shafts) the 9 inch is a stronger and arguably better designed axle. Like the 8" Yota, it's very easy to change differientials in the field. Try that with any other hypoid design....
Don't get me wrong, I have a Dana 70U in a Bronco, and a Dana 80 SRW in my F250. Both running Powerlocks and 12" Chevy disc brakes. I use them because they fit, and neither required a whole lot of fabrication. It was a tremendous strength gain, considering the best bang for my bucks. The loads I move require full floating HD axles and the Ford 9" doesn't come stock with them.
If you want to exceed the Ford 9" in strength, go to a 10.50" GM (Saginaw) 14 bolt full floater, or it's progeny, the 11.50" Dodge AAM axle. But you'll pay the penalty in unspring weight, and ground clearance. That still doesn't solve the front end. IMHO the hi-pinion Ford 9" differential is stronger than a Dana 60 hi-pinion.
Again, I'd steer clear of a high pinion rear differential.
For the money, the Toyota 8" is a helluva good axle. Light in weight, and strength in a economical package.
If money wasn't an object, the strongest, best ground clearance, lighest design above it is the Ford 9". Go hi-pinion in the front, choose your knuckle/hub/brakes. Then a standard Ford (hi nodular iron) diff in the rear set up with full floating axles.
I guess it needs to be stated my argument is regarding strength of the differential, not the area the stub axle is connected to the main axle shaft. I don't have a need to run larger than 32" tires myself. If we're discussing knuckle strength/design, then it's the closed king pin knuckle.
Lastly - I drive where I know I won't destroy my equipment, and don't ask the vehicle to do things it wasn't designed to do.
Happy New Year guys.
