To begin, you take off about a million screws that hold the underbody covers on, then take the heavy exhaust off. You're gonna need help from your fellow workers, because it's very heavy and awkward to remove by yourself. After that, you unbolt the driveshaft from the transmission. I always end up smacking my head on the damn driveshaft while I take all the transmission bolts out. You have been warned! Heavy jobs like this make me nervous because there's always a chance of the transmission moving the wrong way or shifting it's weight too much to one side while you maneuver it out of the car. Also, I always end up soaked with trans fluid after I pop the transmission cooler lines off from the side of the transmission and it starts leaking out. It makes the floor super slippery, so I have to be very careful that I don't fall.
Once I had the transmission out and took the flywheel out, I found the rear main seal was in fact leaking. In this engine (N63) the part comes as a cover with the seal already on it. I replaced the cover, cleaned the area and reinstalled the transmission. The whole job took me about six hours.
