[Marshall V. Daut]

Following up on what Ed posted, the double race in the banjo should not just fall out or be able to be pushed out by your hand. It should be a near-press fit so that it does not spin inside the front flange. I have seen them where the race literally fell on the floor because it was an improperly made under-sized foreign piece of junk that was sold in the 1970's and 1980's in this country.
I don't see that anyone mentioned checking the preload on the two front bearings. The drive shaft should not be able to spin freely. It should have pretty good resistance so that you can still turn the driveshaft with two fingers. If it spins freely, you'll need to tighten the two nuts, especially the one closer to the pinion gear. That's the one that really determines the preload. The second nut merely keeps the first one from backing off. The multi-eared lock tab between them keeps the two nuts from backing off, especially the one closer to the U-joint.
Marshall
Marshall