The drain could indeed be one of the main factors causing the shaft to fail, but I believe the play in the transfer case also plays a significant role. I’ve consulted multiple shops about the play in the transfer case, and none of them considered it normal. I experienced vibrations while driving and ...

I installed a custom spacer that pushes the shaft's splines deeper into the transfer case, which reduces the play and the risk of the shaft failing. Added pics as files.
Email me if you're interested: samuel.soencer@gmail.com