front pump seal and bushing question

this thing does not leak at all while running. it is only leaking when I bring it home and let it sit overnight. i have changed the pan. I have changed the pan gasket many times using silicone only, using silicone with new gaskets. using new gaskets without silicone. I used cork gaskets. I have used rubber gaskets. I have tried all of it. I changed throttle shaft gaskets, kickdown seal. Dipstick tube o ring. when i put it up on jack stands over night, the fluid is eaking out around the inspection cover. The pump seal is the only thing left I know to replace. when I pull the cover and run my finger up around the inside of the bottom of the bell housing, I get fluid. I am planning on putting this car in the Calvacade of Customs car show next January in Cincinnati and I dont think they would approve of a leak on the floor while it sits overnight there. It would embarrass the hell out of me also. I may have to replace the tranny. I have dealt with this all last summer. Any other ideas from anyone. It will leak out a puddle about 12" in diameter overnight. I have even lowered the fluid level some. Someone has told me that it happens when the pump drains back into the pan overnight. Thanks,Bill