The front axle has a vacuum operated clutch which is why we can change to 4wd at speeds upto 50 mph - the same as the trooper III and the frontera B
If you ask on ITOC there are guys who know the exact vacuum pipe locations and colours for the clutch pump its normally just a split pipe or siezed/stuck actuator rod
The electromagnetic clutch is what sends the power to the front prop on the JDM - through the internals of the transfer box - US versions don't have the option unless they fiddle with the electrics -
Muddy****er i have sent you a shed load of info about the SOTF strip and rebuild stuff etc
cheers
Steve