How are the outer axle bearings of a rear-wheel drive solid rear lubricated?

In a rear-wheel drive solid rear axle, the outer axle bearings are usually lubricated by the differential fluid or gear oil. The differential is a device that transmits power from the transmission to the wheels, and it also contains the axle bearings. The gear oil lubricates the bearings and helps to keep them cool. In some cases, the outer axle bearings may also be sealed and filled with grease.