Apparently there is an AC drain which drips onto the exposed section of driveshaft and if not greased properly the splines can dry out and rust. I think some members have moved the drain over to prevent this, but honestly I haven't seen it becoming an issue on pre-facelifts until well over 100k miles.

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2018 Ram 2500 6.7L Cummins 68RFE
19k miles -Bright White/Black - Big Horn Sport - Crew Cab Short Bed
2013 X5 35D (CEO's) - Born on 5/17/2013 -
82k miles - Alpine White/Cinnamon Brown/Premium Pkg, Sport Activity/Premium Pkg and Sound/20" Style 214/Running Boards