Thanks to all who answered.  I'm better equipped to make a decision now (I
like the TBD LSD option, not sure how much dAAryl charges to build one).

Regarding the mention of an extra emergency brake, an acquaintance of mine
who used to raced baja stuff installed a second emergency brake lever right
next to the original.  The lock buttons were removed, so he could reach down
between the seats and with one hand lift or release the levers to shift
traction from one wheel to the other.  Apparently the cables were shortened,
because he only had to lift them a little to have the desired effect, i.e.,
he could grasp both levers simultaneously and rock his hand side to side to
shift traction.  Wonder if this would work in a Vanagon?

Warren in Santa Fe
88 Westy