Nathen,I myself have only blown one pinion gear apart,& that was cause of my own stupidity. Pulling a loaded semi dump w/a loaded 6x6 dump,pulled the shaft right out of the gear.
Now your talkin moving a LOT of weight through one little shaft. I highly doubt you'll be putting your tractor under these kinda loads.Plus the tractor will never get the traction of a loaded dump truck w/locked diffs & fulda tires on it.
The F-350 diffs work just fine, a little cutting & they look just ducky.
With a little time involved,you would never know that they were a steer axle to start with. Just used one in my tractor/loader in the rear,& that baby is heavy.She'll spin the tires in dirt w/no problem!
F-350 axles are everywhere & cheap,you can go through a boat load of 350 axles,before you hit the price of a couple aluminum axles.
Just my .02 on this topic.
FGD