justin@BAYAREA.NET writes:

<<  What does it do? >>

Vanagons, like most cars and trucks, come with an 'open'
differential.  Jack up one rear tire and with the engine running
release the clutch.  What happens?  The tire up in the air
spins merrily along while the tire on the ground doesn't move.
This makes for a nice smooth transfer of power from one
side to the other during cornering.  Remember that the inside
tire has less distance to travel than the outside tire on a turn.
Without this 'slippage' you'd be dragging the inside tire sideways
everytime you took a corner.  The locking diff does just what it
is called.  It locks both sides in so that power is transmitted
evenly to both wheels regardless of traction or cornering.  This
is very nice if you are stuck in the mud or snow and have a
straight line out.   Since both tires grab and turn and the same
speed this is why the owner's manual states that the locker is
to be only used for straight line driving for a short distance or
until you are free.  Afterwards you have to 'unlock' the diff or
play silly buggers trying to take the next corner!

Do you need it?  Depends on how and where you drive.  Is it
required?  No, but its nice to have something and not need it
rather than need something and not have it.

-Todd Hill
 VolksWerks Transaxles
 Olympia, WA
 360-412-0948