360 Rear Bearing Failure?

I have 300 miles on the engine in my Duster and I have been chasing a oil leak , so I figured the rear main seal was done. I dropped the pan and pulled the rear cap and the bearing is toast? The Thrust bearing is fine? Any idea what would wipe out the rear bearing?

Oil and or lack of it. I have a NOS rear main cap for 360

Dirt, out of balance convertor or clutch.

I have a stick in the car and there was no vibration at all, the other bearings look fine. The rear is down to copper and I have run only Brad Penn oil.

Maybe the journal on the crank was messed up?

Could be! I will find out after I pull the motor I guess.
It seems the rear part of the bearing is worse then the front part.