@smoothcriminal - Sorry to hear about the engine!
I should clarify that the bearing that went out on mine was on the input shaft. This is built into the crankcase and is a known failure point. New engines have a newer upgraded bearing. Older engines can be upgraded.
In your case, I wonder where the damage started.
Not good to see!
Do you have any history on the engine, like when it was rebuilt? Who buy? Did it have a seal on it?
There does not look to be any detonation that I can see in those pictures but it is strange to see the plating come off the barrel. It might be the pictures but externally it looks a different colour, I wonder if it has been freshly replated but not correctly, or washed with something it has not agreed with? I imagine the plating has fallen into the sump pan and blocked the scavenge screens for the oil which has then caused oil starvation and the wear that you are seeing on the bearings. The Life data would be good to see, I imagine the starvation has been in the form of oil surge so not dropping low enough for long enough for it to cut the engine - either that or it has been rebuilt with incorrect tolerances.
I have only ever seen the 2nd output gear seize on the shaft when the coupling nut has come loose and this has then loaded the shaft/gear/bearing up on that end.
The wear to the oil pump will be due to the debris in the system.
Make sure when this engine goes back together that you flush and clean through all of the oil pipes and tank, the oil cooler should be replaced.
