The half shafts have no bearings per se. They have a joint on both ends of the shaft. These shafts connect to the side of the differential and transfer torque to the wheels. Because of the independent suspension, they allow the wheels to go up and down while the differential is fixed to the body. On most American front wheel drive cars and pickups, the entire rear axle moves up and down and is spring mounted. This means that the driveshaft connecting the transmission to the rear axle must change in length and angle as you drive. With an independent suspension, the driveshaft transfers torque without changing length or angle. The half shafts are the ones that change length and angle.
These shafts are typically not serviceable by a home mechanic. If you can find a good used pair of shafts, this would probably be your best bet. Failing that, I'm sure that the parts shop on this site has them available at a good price.
'84 Euro 240D, 516K miles
'88 300E 5 Speed
'81 300D Daughter's Car
Over 800,000 miles in