Friends!
My personal experience with the front U-joint was that it was impossible to get a grease gun on the Zerk without tilting the drive shaft down at the maximum angle.
There was a lump of weld on the other U that made the fit too tight even after grinding the Sears swivel tip down some.
So, after examining the diagrams of the drive shaft, I removed the rear wheel and supporting the rear drive so it didn't put weight on the drive shaft, I slid the rear drive back, without unbolting and still supported, until the front half of the driveshaft was free of the splines and would tilt down and rests on the swing-arm hole.
Then with the Sears angled tip it was easy enough come from the back, through the hole in the swing arm, attach to the Zerk positioned at the top, then grease away to my hearts content. That is, until the discolored old grease is followed out of the ring seal by clean fresh grease. That is how I was taught to grease U-joints.
Then with a stip of cloth and a chop stick I clean up. I findle the 36" x3" rag back and forth through the joint in various directions picking up as much proto-fling as possible - go for a short ride and clean up the rest.
I will do this each time I replace the rear tire 3-6,000 Miles (Sometimes I buy sport-touring tires).
I hope this helps others who, like me, shudder at the thought of removing a perfectly good swing-arm.
Craig