Carroll Smith in Engineer To Win was a big fan of shot peening highly-stressed parts like gears. But you need somebody really good to do it, like a shop that's certified to do aircraft work.
If (as Timbo suggests) the newer and later Dweasel angle gears are stronger, it might be worth getting one and getting the gearset professionally shot peened, then do regular lube changes to keep it bulletproof - none of this Sealed For Life nonsense.
