You can rebuild that little box to put in a Hall Effect sensor in it.
A Hall Effect sensor is just a coil, such as a coil of a solenoid.
Make a small disk driven by the speedometer cable in the center
of the disk. Put a small magnet on the edge of the disk. When you
drive, the speedometer cable turns and it turns the disk. Each time
the magnet on the disk passes by the coil the coil generates a pulse.
Feed the pulse to your electronic speedometer there you have one that
should work. It sounds very simple but the quality of the work will
determine if it will really work and reliable. You only need the
lower section of the speedometer cable between the center of the front
wheel on the driver side and that box. The cable between that box and
the original speedometer you can send it to me. It is replaced by a
pairs of wires of course.

You can buy one at a cost of $100+ and still you have to figure out
how to adapt it to your Vanagon.

David

--- Mark Thoma <mpthoma2003@YAHOO.COM> wrote:

> Hey everyone,
>   I need to know how to get a signal for an electronic SPEEDOMETER from a Hall Effect sender.  I
> don't see how the signal from a distributor could be used for anything except a tach.
>   Does that little box at the junction of the two part speedomter cable contain a Hall Effect
> sender??????????????  If so, how do I get a signal from it for the speedo? Which terminals do I
> use?
>   thanks in advance
>   Mark
>