Welsh
Grumpy Mutt
I am posting this in response to post made by Coxwain and the some issues that Dirty Harry had, based on my observations. 
The boxes I have opened due to rumbling bearings, have in all cases so far been a single bearing, always on the intermediate shaft not on the inlet or outlet shaft, but yes while in there I do change the others. On the seals I have seen a couple of issues, it is quite easy to get the seals in slightly skew, they must be in square or they will leak, I don't have the BMW tools may get some made up to drive them in square, I have to set it with the vernier. The other issue is that on high mileage gearboxes, the seals wear a groove in the shaft, these grooves can easily be 0.15mm deep and the edges must be dressed, I am going to set the seals as best I can off the grooves. But the other issue is I have seen corrosion on the shaft just beyond the seal, if the seal runs on this "rust" it is like sand paper and will eat the seal. All I am saying really is be very careful and pay lots of attention when fitting and setting up these seals.
The boxes I have opened due to rumbling bearings, have in all cases so far been a single bearing, always on the intermediate shaft not on the inlet or outlet shaft, but yes while in there I do change the others. On the seals I have seen a couple of issues, it is quite easy to get the seals in slightly skew, they must be in square or they will leak, I don't have the BMW tools may get some made up to drive them in square, I have to set it with the vernier. The other issue is that on high mileage gearboxes, the seals wear a groove in the shaft, these grooves can easily be 0.15mm deep and the edges must be dressed, I am going to set the seals as best I can off the grooves. But the other issue is I have seen corrosion on the shaft just beyond the seal, if the seal runs on this "rust" it is like sand paper and will eat the seal. All I am saying really is be very careful and pay lots of attention when fitting and setting up these seals. 
