that should be a retaining groove for the shield. the shield is sorta like a snap disk, inserted into the groove and then pressed which makes it expand out and lock. oil would enter the cavity between seal and bearing via the oiler hole in the case. the oil level would rise and spill into the bearing between the cage ring and shield. now on start up, oil is retained in the race via the shield so it is not spread out in the void between bearing and shield and becomes more important when the oil is cold and does not flow very well and this applies also to the oil wash via the oiler hole. now as the oil level rises, excess oil escapes into the primary, the shield also protects the bearing from contaminates to a certain degree.

 

The only difference I am aware of between the early and late trannys is the OD of the main shaft where the IPB race lives; the later main shaft OD is smaller in that area and the ID of the later race was made smaller to fit. HD Tech Tip 329 laid out this running change in May 2007. The difference in cost is what? $8? Why not use the bearing designed for the model year?

 

It's not about the cost of the bearing, it's trying to understand the differences since they appear to be the same size. I was surprised that the newer bearing for the late model motorcycles actually cost so much less. I attached the HD Tech Tip 329 you mentioned for the people that might be curious.

 

thought you were discussing the shield
do not remember when or what machine but if it is as djl describes, hd had issue with the inner race walking into the tranny screwing up the oil seal and such, they then put a step on the shaft to prevent this from happening and probably the bearings are diff dimensions since it would be easier to do it that way.
have you mic'd them out or sourced it out via cross-ref.

 

Between the 5 speed and (06/07) 6 speed motors HD changed the inner race and bearing. I've seen both and other than the numbers and the grove on the 6 speed outer bearing race they are dimensionally the same. The 08s changed only the inner race to about 0.008 smaller and made it a little longer. I've used the outer roller bearing from a 08 up kit in a 2000 FXDX and so far it's working fine.

The main change for the 6 speed was the addition of the oil hole for additional lube to the bearing. HD changed moved the primary chain further out covered some of the bearing from splash with the ring gear so they need to add the hole for lube.

 

thanks for the clarification mr. max.
that should address all the issues as to the fit.
personally, i would stick with design, hd just did not haphazardly include the shield. you find this arrangement in many automotive trannys.