sethhatfield - you don't mention what year and version of transfer case you have. When you change the chain, refill with Redline MTL (if you have the NV125) and install a magnetic drain plug (BMW didn't install them but you can get the OEM magnetic version from Automatic, Standard Transmission and Transfer Case Rebuild Kits, Cobra Transmission Parts 1-800-293-1848, Cobra Transmission. You can go "whole hog" and buy two for the fill AND drain plug, which is what I did.

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2002 Euro X5 (E53) 3.0 diesel (M57)
5 speed manual with UUC short shifter.
Pre-xDrive NV125 transfer case (chain & gears).
Factory Xenon headlights, Spyder LED tail lights
Updated vortex crankcase breather.
Motorsport dead pedal, factory fire extinguisher, factory first aid kit, factory F&R mud flaps, factory PDC

Bilstein B6 shocks F&R
Redline oil has replaced "lifetime" fluids (F&R diff, manual transmission, transfer case and P/S).
Dimple magnetic drain plugs in all compartments.