i purchased my 80 300sd in 1994.just shortly after i experienced a metallic grinding noise from the right rear wheel.upon inspection i discovered both axle halfshafts had lost their oil and were totally dry.i repacked with a quality cv joint grease both innner and outer joints and never heard from them again until this winter when i started to hear some knocking again.this time i noticed one of the boots was torn in several places on the outer joint.i beleive these are the original as i have most service records on this car from previous owner.speaks volumes about mercedes quality.i have repacked the joint again and plan to install a new half shaft.meanwhile the noise has disapeared.