@Reinier
If you want to try one more thing with your shafts, try cleaning off all grease and spray everything with wd40 and put them together. Do they still bind?
I had a difficult halfshaft set and ended up spraying everything lightly (but completely) with wd40 and adding grease at the end by using a needle attachment on my grease gun. End result was shafts that moved freely and have worked great. Will see whether there are any long term problems but....
Edit:
I just found my notes on how I rebuilt my last set of shafts. For terminology, refer to the 1973 FSM page RA-10 figure RA-26 showing the shaft components. I capitalized part names from figure RA-26.
1) Clean everything...remove all grease.
2) Spray everything with WD40.
3) Install large washer and snap ring (neither are labeled in figure RA-26) that get installed on the Drive Shaft side of the Sleeve Yoke. This ends up in the middle of the assembly. With these two pieces installed, the Drive Shaft will still slide into the yoke. The purpose of the washer is to limit the spacers / balls from sliding out.
4) Install dust boot onto driveshaft. There are lots of ways to do this but I used wd40 and a socket clamped to a vice to get the boot started. Then, push the boot all the way in and inside out if you can so it is out of the way.
5) Slide the driveshaft into the yoke doing your best to keep the bearing slots aligned...making sure to orient the assembly in the right direction...see figure RA-26.
6) Here is the weird part. Start installing Ball Spacers and Drive Shaft Balls from the YOKE end. This seemed counter intuitive to me but others may think otherwise. Use liberal amount of WD40 (different from what I wrote earlier). Don't let the Drive Shaft move too far into the Yoke. You don't want it to move past the position where the assembly would be the shortest. If you do...Drive Shaft Balls and Ball Spacers fall out. Ask me how I know. I probably did this 10 times before I figured out that I needed to limit how far the Drive Shaft can insert into the Yoke. As I kept adding Drive Shaft Balls and Ball Spacers, I would periodically insert the Drive Shaft Stopper from the Yoke end to push the balls and spacers down farther into the Drive Shaft / Yoke assembly so that I could keep inserting additional Drive Shaft Balls and Ball Spacers.
7) Once all Drive Shaft Balls and Ball Spacers are installed, install the Drive Shaft Stopper (orient correctly) and Snap Ring (this one isn't labeled in figure RA-26).
8- Let WD40 drain.
9) Use the smallest needle attachment for your grease gun you can find and begin injecting grease into the bearing grooves that don't have balls. Move Drive Shaft in and out of the Yoke to distribute grease. Keep doing this until you think the assembly is nicely packed.
10) Pack center and boot with grease and fasten boot.
11) Install Sleeve Yoke Plug and Snap Ring.
Hope this helps.