Plug the valve covers up and put some air in it and try soap bubbling the seal area. I know of several top shelf mopar engine builders who are ready to rip their hair out right now over these dang seals.
Todd

I am not aware of this hole. Does anyone have a picture that shows the location of this hole?

RAMM
Did you happen to tank the block really good before the rebuild. I read a piece by Rick Ehrenburg a few years ago and he stated that some blocks because of poor manufacturing were porous at the rear and were sealed by some coating applied to the block at the factory.He warned about possible oil leaks after a good tank cleaning as it could remove this sealant. In your case it may be seeping just above the crank and presenting itself as a seal leak. I sure feel for you on this one.
Ross

OK,,, I have been through this hell before.
I had my 383 engine built by the best in the business; a professional, 30 year, race engine shop.
First run it leaked on the stand. Second seal...leaked on the stand.
We pulled it apart 4 times.
We checked and sent the crank out to an expert. Perfect crank.

Finally...
He tore the engine down to the bare block. Checked everything with a micrometer. After measuring and researching we found that a small percentage of MOPAR block rear main seal retaining threads are drilled off to one side, ever so slightly. It is literately thousands of an inch off. Enough for a small leak according to Felpro.

He eventually used an OEM rear main seal retainer (they have some slop in the side to side placement. Driver to passenger side movement). He shimmed the retainer to one side the distance it needed to go to center the retainer exactly over the crank and to pull the weak side seal over to the crank surface. If you look closely you will see the weak seal side against the crank. also you will need to have the seal slightly off center in the block and retainer to have the retainer grab and pull the weak side over to the crank as you push the retainer to one side.

This is about component machine errors. DO NOT believe in crap like the type of knurling on the crank end, Rope seal fixes, and other non-mathematical crap. It's all about tolerances and measurements. Something has to be measurably wrong. either the crank is off or the retainer/block is off.
Don't grind the retainer to make it tighter. Look at the seal as it presses all the way around the crank. I believe he said he used a snap gauge to measure the exact distance it was off from center and that measurement is what he used to push the retainer over.

My engine builder now checks every MOPAR block for this error. He spent months on my engine and cost him time and money that he does not want to go through again.

It was a nightmare. I feel your pain. My engine is now dry and runs strong.

Had a rear main seal tryed evry thing the fix. In my case had a aluminum tool made that fit the seal and fit in the main bairing put the lower seal cap on then shine a flashlight from the back the seal was to low at the block shimed the up worked grate. will never install a rear seal without testing the fit.

Never seen or heard of a hole, that relieves pressure off the seal.

Ramm, just try the sealing ends 90* apart can't hurt. And like I said, I never glue the seal in the block or retainer. Just place it in there. Place lower half of seal, put crank in, then take upper half of seal and work it around crank until you parting lines at 90*. Then put the retainer in

Studying this closely I think I may have to provide more clearance between the #5 cap rear and the "deflector" on the crank. The black squiggle is where I could machine .057" off. It may do the trick. I really don't think there is any issue with the seal itself. I am leaning towards a severe oil/pressure buildup that NO seal can handle. I'm also starting to think the windage tray should be left out to provide more room between the rear counterweight and the cap. J.Rob