Grinding From 4wd After Driving on Sand

'05 Doublecab 4wd

Wasn't making this hollow grinding sound when I started, drove on sand for maybe 30 minutes, drove onto road, back into 2wd. Drove 20 feet out so then put it back into 4hi, now I get this sound. Only really audible above 10mph Any ideas of where to start looking?

Not sure how to share videos but here's all Google photo link, hopefully it works
https://photos.app.goo.gl/GGEQ7xGkbmnF5Yan6

 

Jack it up in neutral & start spinning tires. Dry powdery sand or wet sand?

 

In 2wd it's fine, and beach sand, so like medium I guess lol

 

Super sandy where I live. It gets into everything. Probably just in your brakes, but hit anything that rotates with a hose or pressure washer I bet it will stop.

 

It’s an older truck it’s probably caked in some grease from a seal on your driveline or something. A blast of brake clean or just soap and water will probably help break it up.