Current one is made by Cane Creek,
CC Company has a broad range of products.. and so their higher tier offerings may be what you desire ..
you can also just buy a bag of balls of the same size as in those retainers and stick them in the grease that you repack them with
and probably get 1 or 2 more per race in and leave the rest of the parts as is.
retainers are often used in factory assemblies to speed the job up.