transfer case noises

Hi guys,
New to the forum - I'm a YJ guy, but helping a buddy with his XJ. He's got a 96 with the 242 TC.

When we jack up the front and spin the tires by hand, we are hearing a distinct knocking sound coming from the TC (the TC was in 2wd).

When we jacked up the rear and spun the tires, we heard a much quieter sound but sounded like a bearing rolling around in there.

In neutral, no distinct sounds from the TC.

Any thoughts on what may be the problem? I'm not sure what 'normal' is for the viscous coupler and how it sounds in 2wd.

Thanks guys.

The 242 transfer case doesn't use a viscous coupler.

So is the 242 just a larger version of the 231?

No,the 242 is a full-time case vs the 231 being a part-time case.

What is the difference internally? Does the 242 have some kind of differential mechanism?

The 242 uses planetary gears for full-time mode. As far as I know, the front output and the chain always turn with the front driveshaft. The chain sprocket on the rear output shaft is connected/disconnected depending on the mode (2WD or 4WD). So, that means that when you spin the front shaft and hear noise it could be front output bearings or chain.

I may be wrong, but I have had one apart before (to put in an SYE kit with new output shaft).