1999 Plymouth Voyager trans leak

I had my 1999 plymouth grand voyager 3.8l axle seals replaced and the oil pan due to the leaks, well, I still have a trans fluid leak. I was told by my mechanic that I needed the transmission seal shaft replaced, cause mine is cracked.I called around, no one knows this part. My mechanic says its the part that connects into the transmission from the axle, it has four bolts attached to it. I'm not sure what the part is called, maybe it is the housing for the shaft. Any thoughts?