someone in the know give all the possible sources for the rear-end roaring?


Sounds like a semi rolling down the road.

 

Lift & safely support the rear of the vehicle, spin the tires, pull the differential cover, check the brakes, etc. No way anyone can accurately answer this question without you doing at least a modicum of investigation. Listing the year, make & model, 2 or 4 WD, wouldn't hurt either.

 

Tire noise?
Bearings? Check for lubricants.
Any vibrations.
Have a look, take two aspirins, post us back in the morning.

 

Sorry, I must have assumed everyone is a mind reader.
This one is a '99 XJ plain-Jane...not even a Sport.
4.0 auto, 4x4, 140k on the clock. Mint shape visually, motor sounds great. Drove it 40 miles home. No rattling, vibrations, brakes work properly. Just a very noticeable droning sound coming from the cargo bay. No heat detected by fingers on drums.

 

I had a similar thing on my f-150 a few years ago, the roar transmitted up through the driveline and sounded like it was coming from my transmission.

In the rear end, either the pinion bearing itself or the pinion crush sleeve had given up, I forget which.