My driveshaft splines and TC output gear stripped at 136,000 miles. The local dealership installed a new driveshaft and a used TC that had 76,000 miles on it at the time. They would not warranty the work unless a new, BMW driveshaft was used. I've driven the vehicle another 139,000 miles since then without any problem. The service manager at the dealership assured me that none of the vehicles they had repaired had come back with the problem again because they were sure to really pack the spline joint with heavy grease. I have to admit, the original one was bone dry and had literally rusted away badly when it failed.

2002 X5 3.0 275,500 miles
2004 325i 119,500 miles