Rear main oil seal

[4 pot truck]

After a 1000 mile round trip my engine developed a major oil leak from the back of the engine inbetween the flywheel housing and engine block.
I thought it was going to be the gasket between the flywheel housing and engine. Now I have drained the oil I have found big bits of what I think is aluminium. Could this be the rear main oil seal broken up? Has anyone got experience of this? The engine was running sweet apart from the oil leak.
I know I am going to have to tear the engine down but I just wondering what to expect.
Thanks Andy.

 

[CarlG]

Could be babbitt from one of your mains. Just had that same thing happen to me, after a 1,000 mile trip.

 

[700rpm]

Babbitt is gone. Time for new.