Have a 1999 1500 4x4 w/ manual 4x4 shift. At speed above 30 mph there is a whine coming from the rear end. Oil is full, no leaks anywhere. Thinking a bad pinon bearing or even a carrier bearing but why only after 30 mph and not all the time. Any replies with same problem or what may be the problem would greatly help. Thanks

 

Have you had the truck since new? If not, did it have alot of towing? How many miles?

 

May not be as noticeable at lower speeds. My brothers did the same thing before he finally blew it up