Drilling drive shaft on X6

[Windy]

Hi Guys

Have got the standard B4 driveshafts fitted to my X6 and have noticed that with the droop on the rear the driveshafts unload from the cups when the car is in the air. Have heard that you can redrill the shafts but unsure on how much that they need to be redrilled and is there enough thread on the remainder of the axle?

Thanks for the help

Windy