Weird low hum and vibration in reverse

So it snowed a lot in Utah today. Went out with the family and drove through the snow. Ended up pulling someone out of a ditch with the winch (I was in neutral, don't think I could have broken anything), but otherwise it was very uneventful. However, when I got home I noticed that in reverse my truck is making a weird vibration noise. Any ideas?

My skid plates are packed full of snow and mud so my hope is that it’s some sort of resonance vibration between my rerouted exhaust and the skid plate with everything that’s packed in there, but I’m a little surprised it would only show up in reverse and when I’m actually moving. I thought about waiting to post this til it melted but it could be several days and if it’s an issue I’d like to get it looked at ASAP.

 

Any conclusion to this? I might have a similar noise that I'm trying to solve. Only happens in reverse between idle and 1000 rpm. I have skid plates as well and it only happens with the skid plates installed or they are just bouncing the sound into the cab. Curious if you ever found out what was causing yours.

 

Mine is gone now. I wish I could tell you what I did to fix it, but I can't. What I can say is that at some point between trips and car washings it went away.

Initially it did go away after the snow melted so I thought that was it. Then I noticed it again after washing my truck. At that point I thought maybe the issue was water getting into the muffler accidentally. Since that time I have been more diligent about cleaning under the vehicle and not spraying water into the tailpipe and it has not come back. I think it's just a harmonics issue (or at least, for me). Try giving her a good clean, maybe even taking the skids off to get all the rocks out from in there (I had one the size of my palm lodged in there).