[Keithc8]

The 460 has a similiar problem in that the flange of the crank is to big for a one piece rear main seal. we have even thought about having 460 and FE cranks made with the same rear on them as the small block Ford and then use that rear main seal. This would mean new flywheel bolt pattern as well as flexplates. I lot of trouble to fix the two piece seal short coming. We have not had near as much problem with the 460 rear seal but what we do is put a little silicone on the back side of the seal, turn it where it is up a little on one side and down on the other where it does not line up at the parting lines. We also use a little silicone between the cap and block where they meet. This has worked pretty well for us in most cases. If the block is line honed it will tighten up the area where the rear main seal goes. Hope some of this helps but these are probably what you are already doing.

Thanks, Keith