CowThrasher ...... Just my $0.02

A good quality 'sealed' U-joint has lasted longer than the greasable joints for me.
When pumping grease into that U-joint, the grease always goes to the quadrant with the least resistance ..... the remaining three quadrants will go without lube.

Ladysmith B.C. here .......

 

Had similar problems w/my '93 W250... did all you did - rotated my tires: ront to back: problem solved. However; recco you look at the steering gear to frame bracket for failure. Seems it's a common design failure (power plant torque to allignment to steering forces-5.9L, Series B intercooled engine). The bracket is not available via Dodge. I jury-rigged mine by chaining the steering gear box to the frame (my bracket break was only on the front-end) - a welding fix will stress fail quickly. The entire front-end and steering become loosey-goosey with age/wear. The fix -I believe is spending the bucks to beefing up the steering column, steering gear to frame bracket and frame to handle engine torque. If anyone out there knows how to do this, please let me know.