A while back a guy posted that the way to install a rear main (on say a 350 w/ the 2 part seal) is to clock it 90* and thus have the 2 halves meet in the center of the cap.

Anyone heard of this? Was he cracked out? Is there truth to it?

My 350 has a leaker. It seems to only leak when I'm driving it as I stuck it on the jackstands the other day and ran it at about 2000 RPM for 10 minutes and it didn't leak a drop. Do they only leak when the oil in the pan is shifted back against the rear seal?

Any help is appreciated as I hate to do this wrong.....again.
Thanks,
-B.