Look
Several things have contributed to all the rear seal leaks in the recent past
NUMBER ONE--Fel Pro rubber seals have gone from good part we used trouble free for years to an inferior part that does not even look like the old one--is a DIFFERENT size than the old one and will NOT seal like the old one--cause? maybe the tooling is worn out yadda yadda but I think it is offshore crap from company that does not give a S$%* about its customers
NUMBER TWO The offshore cranks have wicked copy cat knurling with no idea in the world why it is there--what it is for or HOW to put it on correctly thus you have a ripsaw effect on any rubber seal and they leak!
NUMBER THREE Some of the billet retainers made from some outfits were defective and held oil up against the seal causing a leak--there were even folks advertising those as "modified" to help this designed in defect.
NUMBER FOUR Crank grinders "smoothing " up stock crank knurled areas in order to prevent the dreaded Leak which will happen for sure when you take too much off the seal diameter of a stock crank
I enjoy building other brands that have good seal designs and don't cause me a PIA with rear seals.
I now use the orange rubber with the BLUE side seals that are advertised on here and they seem to work well though I truly miss the asbestos side seals.
There are other factors with factory seal holders that get into great detail like the spot face for the bolt heads etc etc way too much to go into and...if you are a smart builder you take that seal holder and bolt it to the bare block and Observe how the thing lines up on that block and if you have to move it to get that right--well then which way? and then you mark it with some scribe lines so you can duplicate that precise line up when a seal and a crank are present thus ensuring that the two seal halves meet just right and even then it may still leak when a customer runs it with No PCV hooked up--that very slight vacuum helps out a lot! So........................
Just my 2 cents worth, carry on
