So on my junkyard 820 i needed to clean the axle, perform maintenance. The cassette gears were rusted on one half most of the time, maybe being in the air or grease for years. So i found a good method on how to remove this rust, you don't want this floating around in the tranny.
Things i used:
Corded drill
wire wheel
gloves
safty glasses
This is how i held it. i used towels fo the machined surface wasnt damaged. I used a papter towel becuse the wheel catches it sometimes, and just blows it apart vs getting wrapped up
Ew
It is slightly pitted, but i used a screwdriver and coildnt get any debris out of it. So id call it fairly close to good.