Just make sure you NEVER use 4-Low on dry roads! It needs the poor traction of snow, ice, or dirt to keep the axles from winding up.
On the other topic... Do you guys agree with this? I've never heard that before. I have heard that you shouldn't exceed 25-30 MPH, which is the advice I've been heading.
Believe it!
4-Low + hard pavement will eventually = *snap* *crackle* and/or *pop*

The driveline on Isuzus is not intended to be engaged without some slippage coming from somewhere - be it the TOD system in High-range (if so equipped - like our VXs), or a loose and/or slippery surface.