I find this thread very confusing. Hopefully I am not being too priggish.
I have a 1946 turbine motor in front of me (spur gear), a Lionel service manual, and 1947ish turbine motor with the loose ball bearings. (The manual describes a variation on the motor, not certain which one this is)
This 1946 spur gear drive turbine motor does not have any ball bearing at all. The service manual does not list or show loose ball bearings for the 1946 version of the 671 (2020) Turbine, or for the 1946 version of the 726 Berkshire.
The worm drive turbine motor with the loose ball bearings has twelve bearings in the race closest to the worm. They fit comfortably, but that doesn't mean that Lionel used that many. I probably filled the race when I replaced the lost originals. (I did the same thing as the original poster).
The brass bearing assembly with five trapped ball bearings carries part number 681-121, which leads me to believe that it was first used in the 681 locomotive.
PRR6200s2 mentioned a Lionel service manual page with an entry where the ball bearings can be counted.
So far I have not been able to find it. Perhaps the detail was shown on the 8-47 version of the page shown below.
If possible, I'd appreciate having a page number.
Here is a page showing how the motor goes together:
