Technical Yoke needle bearings

How many needle bearings should a yoke have? As many as will fit? Or should there be one missing? I know I didn't lose any, it's what was in there. Both are this way.
Tri-5 rear end in a 53 Chevy.
The needle retainers (or caps) say Spicer on them.
Sorry for the most likely wrong names for parts, this is the first time I've dove into a traditional RWD rear end.

 

Looks to me like your missing 2

 

Just one. I took one from the other unit, just to make sure another one would fit. One fits, but not two.

 

It should be full, you're missing one.