Hello Chris, having now spent some time underneath my car I better understand your leak. I guess it's coming though the rectangular slot (about 20 x 5mm) thats at bottom of bell housing.
So have to agree most likely is RMS? When I have a chance I'll have a look at the BMW M62 engine info I have to see if there's anything about RMS changing.
Guess most dealers will be able to confirm but I suspect the gearbox is removable from underneath, though can imagine that access to some of the upper bell housing bolts is tricky. Reason I say this is that the rear gearbox support appears to be removable. There seem to be two bolts per side that are hopefully accessible from the inside of the car.
Cheers
