A rear differential fluid leak can occur due to a variety of reasons, such as worn-out seals, cracked differential covers, or damaged axle seals. Symptoms of a rear differential fluid leak include: (1). Puddles under the rear of the vehicle. (2). Whining or grinding noises. (3). Vibrations or shuddering. (4). Burning smell. https://infomeabout.com/rear-differential-leaking/