The rivetet version is not to be rebuilt !!!
Once you see damage , there is no doubt...
Test (if you see no damage):
Hold the U-joint at one end and shake it.
Once it wobbles without resistance and you hear noises....
ITS TIME TO REPLACE !
The "new" parts to be sold by the vendors are not best quality.
(Any new junk will be even better than the ones in those pics.)
Use lots of grease !
Have fun
Chris
I replaced the U-joint in my car with a "new" snyders U-joint 5 years ago.
Even it looked like a strange rough log, its still "alive"