Is there any way to PERMAMENTLY eliminate rear main oil leaks?

Well if the seal is installed correctly other issues could be the sealing surface(groove in the crank where seal contacts the crank or the part itself.) If the crank has a groove meaning any imperfection where the seal rides it may be sleeved? I do not know about slant 6 maybe a machine shop guy will chime in ? I do know Ford 5.0 had a sleeve kit years ago for the one piece rear main that always leaked due to a crank groove. Sleeving is just 1 trick that I can think of at the moment. Point is you have to eliminate down to what it is, bad sealing surface, improper install or bad /wrong parts etc. If sleeving is needed but is not an option a new crank may be needed etc. Also think how bad is the leak? is there huge spots under the car? is it needing 1 quart a month during regular driving is it acceptable? etc. I had made mention that 70s cars always leaked once online and some guy chimed in "not any 70s car that I've ever owned" I replied "you musta bought them new?" :lol: