Drivetrain

Typically a small rubber snubber that cushions suspension contacts (or prevents them!). Often replaced with polyurethane ones for better longevity and different characteristics (lower/higher profile, hardness, resistance to elements, etc.)

You can use 4wd (4x4 Hi/Lo) whenever you need additional traction when accelerating - 4wd will not help you stop in slippery conditions. You can safely use 4wd on sand, snow, ice, mud, etc. - do NOT use on dry pavement or even in the rain. Your drivetrain may bind and be damaged if the wheels cannot slip to relieve tension.

Yes, an incredible advantage. Lockers ONLY provide extra traction IF one tire will LOSE traction. With the front (IFS) suspension on the Xterra, the limited front wheel travel increases the number of situations where one tire will lose traction.

For this reason, a front locker makes an enormous difference, by helping to keep the front end pulling.

People who have added a front locker have experienced a giant leap in their capabilities, without additional breakage over rear locker applications.

Stop your Xterra. Push down on the transfer lever, and pull back towards you.

Reduce your speed to under 25mph (40km/h) and move the transfer lever sharply to 4H. You do not need to depress the clutch pedal and you may experience a "clunk" which is normal.