[Hope Springs Hauler]

From my test drives of XJs, it seems to me that the viscous coupling is active when it is in 4wd Fulltime. This would be the setting to use for slick onroad situations.

Switching to 4wd part-time locks the coupling and it becomes like a traditional transfer case.

The danger in wheeling in "fulltime" is placing a lot of stress on the t-case if 1 wheel were to spin and the rest have great traction.