>With the front DS disconnected the front plates will not turn at all. The
>faster the van goes, the greater the speed differential between the front and
>rear plates, the greater the heat build up. Finally the VC either melts 

Way off base.....  the VC is in the front diff. Connected to the front
pinion gear shaft and driven by the main shaft. Drop the main shaft and
power into the VC is cut BUT IT STILL SPINS. Now its driven by the pinion
gear shaft and spins unloaded in the breeze. The selectable 2/4WD version
replaces the VC with a solid shaft.  You don't suppose that when you select
2WD the van comes to a screeching halt do you?  ;)  Tim