Clutch Bell Housing Problems of Chevrolet K2500

Clutch pedal slowly started getting harder to depress since new (I am the original owner). I put on mostly highway miles for the first few years. First the clutch pedal to rod bushing/retainer would wear out causing clutch to suddenly engage with no warning. After multiple bushings, the clutch master cylinders started failing from too much hydraulic pressure. After a total clutch system replacement at 140k miles, we found the root cause to be the fork and ball stud ate into each other due to insufficient lubrication. Clutch worked like new after replacement. At 160k miles clutch is back to very stiff and parts are now failing again, even with often greasing thru bell housing zerk fitting for ball stud.