When you turn left (above 40 mph) you are loading the right side and unloading the left and you would hear the bearing roar if your RF was bad - opposite is if the RF bearing is bad and you take an off-ramp above 40mph or so it would get whisper quiet as there is less load on it.

When I did mine, only the RF was making noise, but I always recommend wheel bearings and suspension parts be done in pairs so I did both.

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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