Sounds like bearings are worn,
Or they aren't shimmed properly.
No big deal, just need some fresh bearings and seals, and set the preload up properly.
It's all in the Manual. No big deal.
Uh, Aaron, that was posted almost 8 years ago by someone who apparently has been banned, or at least has been active on the board for years. I don't think he's still looking for an answer.
On the subject of replacement 1-piece shafts for the AMC 20, keep in mind that some kits use bearings and seals that are not as readily available as stock parts. If you have to replace one it might take a special order. Also, the tubes on the CJ version are known to be weak and can be bent if overloaded well past their intended use. Probably not a concern with a mild tire size increase, unless you plan to do Dukes of Hazzard jumps.
