Joel's 2 cents:
> aluminum???? well ... that definitely ain't rods or bearings. but it could
> be the case. :(  you said you put a heavy flow oil pump ... any chance it's
> cutting into the case??? that would also make a helluva noise.
> 

Ahhh, the high flow oil pump (incredulous voice per Click n Clack 
Bros.).  Now there's a thought.  Extra tall gears cutting into the 
housing/cover.  Al bits to be sure.  Seems like that would be more of 
a even, continual scraping noise tho.

Waiting with baited breath....