I have the same thing going on in NP 231 with 135000 miles on it.
I was always under assumption that there is a gap between output shaft and bearing that caused this play, but no amount of yoke nut tightening had any effect on it. After taking TC apart, i saw that entire bearing is moving in and out inside of the housing. I did not dig any further as i don't have time or replacement parts to deal with this issue at the moment.
However, question is why?
Looking at the diagram, other than a snap ring (24), i don't see any shims to go in between the hosing and the bearing.
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It looks like outer race shows signs of spinning, but it don't look like it is spinning to the point of shaving aluminum away from the housing, at least oil never showed signs of that.
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A possibility that PO retardation has made its way here and he has forgotten to put snap ring in, that possibility has crossed my mind, but it has been way too leak-free for that to happen. So now i am thinking, it either always has been like this, or something was slowly shaving away for the past 135000 miles.
Best case scenario, a new bearing and snap ring will get rid of this play.
If it does not, hopefully i can find a shim to put in between housing and bearing.
Worst case, there is too much play in the housing. I don't feel any up and down play, but you know how feelings are.