This reminds me of a plroblem I had years ago. I had a pump bushing failure twice before finding this little issue. Try looking at the dowl pins on the block and make sure that they are sticking out far enough to completly engage the mating holes in the transmission. In my car, the tapper on the dowl pin only engaged into the chamfer of the case and allowed it to move around. The end result was leaking converter seal and worn bushings.
Allan G.