BP Series 1 - Identify Bull Gear bearing retainer sleeve

[dansawyer]

I am building a composit BP Series 1. I purchased BOSS 5 base and head from the bull gear down. I found parts from the bull gear up from a BOSS 8. The good news is there appears to be commonality for the drive mechanism. Attached is a picture from the bull gear assemblies.
The one on the left the bearing sleeve is notched at the top and held in place by clips. The one on the right the sleeve is continous and held in place by a key.
I cannot identify which one is newer?
Does anyone have a history of when this change was made?

 

[dansawyer]

Partial reply: I found a video that reflected to one on the left. It looks as though that is the one I should move forward with. The bearing seems to be OK.
However the video shows a threaded 'splined gear hub'. Does anyone know the purpose of the threads?
The mill is a BOSS Series 1 CNC machine.
The gear hub in the manual models is threaded with the auto quill feed mechanism. This mechanism is missing in the BOSS models.

 

[dansawyer]

Speculate Answer:
1. The manual origen machines had a half machined bearing hub and a thread quill feed.
2. The early BOSS machines removed the threads.
3. The late BOSS machines removed the half machining.

 

[hwelecrepair]

The one on the right is from a "rigid ram" (as I call it)/CNC mill like a boss.

Jon