I was looking into this also.  There are companies that make them.
Lock-Right makes one.
http://www.desertrat.com/lockright/lockright.htm  This company caries
them and they are listed for Vanagons.
They run about $250 and you need to pull out your tranny to put it in on
our vans.  If you end up going this way let me know.

Blake Heinlein
irstudent@csuchico.edu   -   work account  -  (530) 898-5623
bhein@ecst.csuchico.edu    -   student account  -  (530) 345-7179
http://www.ecst.csuchico.edu/~bhein/
College of Mechanical Engineering
California State University, Chico

> -----Original Message-----
> From: Johan Nyberg [SMTP:johan.nyberg@ABC.SE]
> Sent: Friday, June 12, 1998 7:57 AM
> To:   Vanagon@VANAGON.COM
> Subject:      Aftermarket diff-lock for Vanagon?
>
> Hello Vanagoners
>
> Not having the dough for a synchro, I'd like to know if there is any
> possibility to install some sort of diff-lock in an '86 VAnagon.
>
>
>   ************************************************************
>     Johan Nyberg, Sweden N 59o E 17o 25"
>     '86 Caravelle C
>   ************************************************************