I had the same problem. Turns out it was just DW popping a beer (she loves my driving - not)
. It might be good to have someone walk along as you tow slowly to see if it happens more than just when leveling. I was told about an axle noise as I pulled into a CG a couple of weeks ago. Will check this weekend with DW walking along side.
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Steve & Diane
2015 Montana 3402RL
2017 F350 Super Duty Lariat 6.7 Powerstroke, Super Cab, Long Box, 4WD DRW
18K PullRite Super 5th ISR