Again I 100% agree with Cab,

A couple of suggestions:
1. Put a fuel pump pressure tester / vacuum gauge on the dipstick Tube with your breathers in place, start the motor and see if it is in fact building any crankcase pressure. The gauges are cheap and available at almost any parts house, harbor freight etc.
2. I might at this point either find a shop with a Dyno that can run the motor while observing the back side,
3. Put dye in the oil. Start the motor and run it for a bit to make sure it's mixed.
4. Brake clean the cr-p out of the back side Leave it sit and do it again.
5. Start the motor and shut is off as soon as oil appears.
6. Pull the trans etc and see what the dye reveals. You could have a porosity in the casting or something else going on
7. Maybe buy or build and engine run stand. One can be fabbed up fairly cheap, especially if you don't have to run it for more than a minute or two. And should you have to, using a garden hose, fill the block with water. Put a restrictor in the outlet hose that will allow enough flow to keep the engine cool. You should now be able to see exactly where the leak is. NOTE: The motors don't require a lot (stand wise) as long as you don't start flogging it. I've seen more than one instance where they were started sitting on the oil pan. NO KIDDING!!!

For some reason I question the following: My BS detector is smelling a bit warm, not quite melting yet but warm
Good luck and keep us posted

Believe me, I've lost all trust in the company as well. The seal was definitely changed because it was a different one than what I last put in before it was taken back to the shop. I wouldn't be surprised if they didn't change anything else that they said they did though.

Here ya go, just to clarify, I'm not suggesting that you hang your motor on and engine stand and wing it, but rather show you that it doesn't require that much to stabilize a free running engine, Do keep us posted

Nice video. I'm waiting on testing for any pressure. I have to buy a new dipstick assembly since the engine builder lost that as well.

Have you tried clocking the parting line on the seal in other positions yet? There were guys on here that clock the line at 6-12 and claimed it never leaked again.

Gus

Yes, I clocked it at 6 and 12, still leaked. The last seal that I put in was one of the fast fish one piece seals and retainer setups. I've only ran the car for about 10 minutes and it hasn't leaked. Just hoping to find out the cause so that this one doesn't start leaking.

I installed a Wenger PCV on my car and the engine runs better and there is no more oil residue around my breather now so it's doing something. I always have a slight drip on the bellhousing but it doesn't leave spots wherever I park it. I'm using a Fel-Pro seal with a billet retainer from Mancini's . I would try a PCV

Gus

Hammering flexplate/flywheel on the crank with an impact? I watched a guy put multiple rear main seals on the back of a cranks....hammering the flexplate bolts everytime with a gun. Finally realized the seal surface was now fubar. The fix was a new crank. Just saying.....

Flywheel bolts were always started and torqued by hand. I never used any impact gun used on the engine.

When did you install the new seal and retainer ???
You changed two items at the same time so at this time there is no way to know which may have been at fault.

Did he loose the tube or did he break it off in the block?

Their are only four places oil can leak at the rear of the motor, above the main seal, oil galley plugs and cam plug, oil pan gaskets, the main seal itself or the main side seals
I use adhesive silicone to seal the side seals after the main seal holder is installed, I also use a very thin strip of that adhesive on top of both main seals so they seal against the seal holder and sometimes a tiny dab on the seal ends where they touch. I use a putty knife or a wide tip thin screw driver to smear the silicone into the gaps on the seal holder to the block, it is not easy but I do it so you can to
i build lots of Mopar B, RB and 426 hemi that don't leak oil from the rear
I hope this helps

The most recent time I changed it, I swapped in a new retainer with the one piece seal, since I bought it as a kit. Every other time I changed just the seal, or the engine builder did, it leaked.

Lost the tube and dipstick assembly.

The leak is definitely at the seal area. I checked all plugs and everything above the seal area and it's bone dry up there. I've tried every combination of rubber seals, viton seals, different brands, one piece, two piece, I've used the side seals on the retainer, left them out and used rtv using the same method that you used, clocked the seal at different locations and no matter what, it leaks everytime. That's why I was asking about a vacuum pump or even going to try a pcv setup because I have tried everything possible that I can think of with no luck. Even after pulling the engine back out and sending it back to the engine builder, waited over a year to get it back, put the whole car back together, just to have it leak probably half a quart of oil in about 30 seconds of running. I'm just want to drive my car at this point. It's been sitting in the garage for two years like this.

I am getting a bit confused,
But if I am understanding you correctly, You now have no leak after running the motor with the FF seal for 10 minutes with no dipstick tube Correct ???
IF so, get the dipstick tube installed. Attach a fuel pump tester / vacuum gauge to the dipstick tube. Start the motor and see if it starts building pressure. It should not with 2 open to air/ atmosphere breathers on it.
Slowly increase the RPM while watching the gauge. It should not be building any pressure.
Next take it for a drive again while watching the gauge.
If at any time it starts building pressure with two open breathers you have a ring seal issue. PERIOD!!!
Nothing is going to fix the issue if there is one except correcting the problem.
The GAUGE will answer the question PERIOD!!

Yes, you are correct. The current setup is the ff one piece seals and retainer. Although I have only ran it for about 10 minutes, it does not leak. The dipstick tube was lost by the engine builder and they just plugged the hole where the dipstick would go (no, it is not leaking here either, I checked that as well). I'm going to do the vacuum/fuel pressure gauge test that you recommended. I'm just waiting on the dipstick that I ordered to come in. I'm really hoping that it isn't a ring seal issue since I just paid a ton of money to try and see if the engine builder could fix it and he changed the seal and said he put new rings in it. At first after I put 4 seals in myself and they all leaked, I thought maybe it was just me doing something incorrectly, but after he put two in and they both leaked, I've always had it in the back of my mind that there is alot more going on, and the shop is just trying to stick me with something they messed up. The last phone call I had with them after I told him it leaked again, he's trying to blame the leak on the transmission being out of alignment, and it's pulling down on the crank. Factory bellhousing, hemi a833 and transmission crossmember, nothing custom, so that's complete b.s. . I've accepted my losses at this point and I'm not even bothering to call them anymore. The company is a joke. I will keep everyone posted with the updates when I get time to do the test. Thanks again, I truly do appreciate everyone's help.

This didn't happen to be one of the old MP crate 528 motors did it? I seem to recall those had lots of issues.

What he is saying is possible but IMO unlikely. It would require a lot of misalignment to do so, not to mention putting pressure on the rear main bearing, the trans would be difficult to put in, and it would likely have shifting problems.

However, I do believe the service manual recommends dialing the bellhousing if changing from a assembly line installed unit. They do sell offset dowel pins to correct misalignment issues. It can be done in the car preferably on a lift but either way it's a PITA.
Or you can do the pressure test and go from there

I've read a lot here about the possibility of excessive crank case pressure. Do the breathers leak? Did it ever blow the dipstick out? If not why do we suspect it is excess crankcase pressure? Have you blocked the breathers and dipstick tube then added low air pressure to the crank case and watched the seal area with the engine not running? With this many seals it raises a few questions to me. Has the seal bridge been checked for proper alignment without the crank installed? Have the bridge mounting holes been opened up to allow the seal to center itself? Are the side seals pushing it off center? Is the seal bore concentric with the main bearing bore? Has the crank main seal area been checked for surface finish and cracks? My bet is many of these items haven't been addressed? Obliviously the engine assembler, not engine builder, hasn't done their job either.
Doug