BMW X5/X6 have been plagued with the front driveshaft issues where ujoint would blow up and shaft would make a hole in the transmission housing or engine oil pan. This will also take out the transfer case splines and would result in extremely costly repairs (7-13k and weeks of downtime).
The actual issue is that the stock driveshaft only goes in about 20mm into the tcase leaving about 20mm more of the unused spline area inside the tcase. With such small contact surface this eventually will result in wear in both tcase and driveshaft splines causing excessive movement and stress on the ujoint closest to the tcase, wearing it prematurely and causing it to disintegrate taking out tcase and either motor or transmission.
I cMe up with a custom yoke mold that utilizes 20mm longer spline section, uses factory dust boot, as well as using larger ujoints that are now easily serviceable (UJ398 by SKF ), heavy duty yoke and differential flanges. My driveshaft will save you thousands and weeks of downtime and is designed for a piece of mind knowing that you wont end up blowing a tranny in the middle of nowhere. Nobody should blow a tranny and we are here to help you stay safe and sound.

PS email me to place an order, i have first 10 units out, fit and finish is excellent, these are made in usa and are designed to save you time and money