Id pull the axles out and send them both to get rebuilt. It cost about $90.00 an axle, and you wont have to worry about the grease. I just had both of my front axles rebuilt. If your gona reboot them you may as well have them rebuilt. I know a drive line shop that only does drive axles and shafts. Its worth it.
Sent from my DROID RAZR using Bimmer App