Rear wheel moves IN and OUT when car jacked up, Outer bearings good, inner bearings/ differetial good

When the car is jacked up I can push the wheel in and out AT THE EDGE
of the tyre by about 1/2 inch The half shaft is good, there is a new well
seated outer bearing and new inner differential bearings, since the half
shaft can only move a fraction of an inch within the bearings what else
could explain the amount of IN OUT movement at the tyre rim. Its like the
differential end of the half shaft is loose ( It isn't and that area is fine).
Any suggestions?? FORD THUNDERBIRD 1963
The only thought I had was that the drum outside could be distorted
allowing the wheel to "Rock" slightly??