In Reply to: Re: Found the cause - This looks like a major issue posted by TheOldHokie on April 20, 2019 at 13:41:16:
I don't recall any work on the differential after Dad passing. However, I don't have memory of what Dad might have done on the tractor. I do recall that water got into the hydraulic/trans fluid unknown to Dad and he started the tractor one winter with the water frozen. I also know that the hydraulic pump was rebuilt, which means removing the PTO shaft and I would think that someone would have mentioned the scarring on the shaft. I just don't have the memory to answer your question. Is there any way I can learn from observation; jacking up the tractor and spinning the wheel? I also have an inspection camera that you plug into the USB port on a laptop that I can use to see inside.
The broken part is 7/8" in diameter. It is also hollow with two flat areas on either side. As you can see, it ground against the PTO shaft for a bit.