Yes, on the early dashes there are 2 brown wires going to 2 different
pins on the 14 pin connector.
The tach dashes have only one. If you pick the right one to use, the
tach dash will work. If you use only the other one, it won't.
The proper course of action is to connect them both to the single
location on the tach dash.
One of the brown wires is the chassis ground for the dash, the other
goes off to the emergency flasher switch light and the rear defogger
switch light. That is a screwy setup but that's what VW did on those
early models.

Mark

Gregory Smith wrote:
> ...................... By using the various
> messages to make sense of each other, I was able to do
> the upgrade without too much trouble.  I ran a green
> wire from the coil to the dash area by parallelling
> the main loom under the vehicle.  I slipped the wire
> into the harness loops and was even able to string it
> over the fuel tank using a flexible-grabby-tool thing.
> After figuring out that I had to combine a couple of
> the original wires, it works great...........