I have a lifted 94 Dodge it went down the road smooth as can be. Took the truck to a mud run that had clay , spent several hours wash afterwards. Then drove to work i had felt the vibration come from the front so took the front driveshaft off thinking bad u-joint nope good drove it w/o shaft and still had problem. Replaced all of the steering system still have the problem. Now if I come to a stop with the the noise it goes away but while sitting if I pump the brakes I hear a crushing noise from the rear.

 

Check for mud on the inside of the wheels.

 

And inside the drums.

 

I tore the rear end apart clean everything and still have noise, its weird now b/c when I put in gear I can hear a funky noise from the rear axle area the u-joints are good and pinion bearings

 

Crunching = Toasted LSD clutch disc's, take off the rear diff cover and look for little or big bits of steel in the pumpkin.