When we changed the clutch, the center ends of the drive shaft dropped down into the gravel (when pushing the car off the hoist) and the universal (with ***** and cage) came off.

We cleaned everything up as goods as possible, put the ***** and cage back in (difficult) and greased it up again.

With everything put back together, the first short test drive resulted in loud clonking noise under load (without load, no noise) coming from that universal/drive shaft.

What do we need to look out for when taking it apart again?