Well the GW site has plenty of factual errors mixed in with lots of good
info.

The speedo cable on 2wd is driven by the left front wheel, not by the
type of fuel in the tank. Diesels used the same wheels and tires as the
gas models. The cable rotational speed calibration number is marked on
the face of the speedo, by the needle shaft. Same number, gas and
diesel. 805 for mph speedos with push-on cable.

As another example of factual errors, that speedo listing at GW says
that 80-83 speedo use a screw-on cable. In fact 80 and 81 did.  Based on
the many 82 and 83 vans I have owned and worked on they use the later
cable. I am looking at a couple of my spare speedos right now, marked
with 5/82 and 6/82 date stamps on the back and push-on cable fittings.
Also if you look at the VW Factory Parts Data they show that starting
with vin#000001 of 82 model year the speedo uses the newer type cable
attachment. Of course the factory parts listings can have mistakes too
but my experience matches VW in this case. What about your speedo,
screw-on or push-on cable attachment?

Mark

Ralph Meyermann wrote:
> I dunno, just what I read on GW about theirs.
>
> Velma 82 1.9L AAZ TD Westy
>
> On Jul 30, 2014 12:02 PM, "mark drillock" <mdrillock@cox.net
> <mailto:mdrillock@cox.net>> wrote:
>
>     The speedos are the same so I assume you mean the tachs. The gas
>     tach gets pulses from the ignition coil and diesels don't have
>     ignition coils. The diesel tachs from the Vanagon era use a much
>     different signal from the alternator "W" lead.
>
>     Mark
>
>
>     Ralph Meyermann wrote:
>
>         I think the diesel one hooks up different or the pod is somehow
>         different. I went from a 185/75/14 to a 215/75/15, just by
>         guessing/eyeballing I'm about 5 faster than Speedo shows. I
>         would like
>         to keep up on my mpg while tuning my fuel/boost for happy oomph,
>         temp
>         and fuel economy without over taxing my Power Plant. My phone
>         doesn't
>         have good enough signal to use its gps
>
>         Velma 82 1.9L AAZ TD Westy
>
>         On Jul 30, 2014 7:33 AM, "mark drillock" <mdrillock@cox.net
>         <mailto:mdrillock@cox.net>
>         <mailto:mdrillock@cox.net <mailto:mdrillock@cox.net>>> wrote:
>
>              The "W" factor has to do with the tachometer, not the
>         speedo. The speedo
>              and odometer are driven by a cable that does not know or
>         care what
>              engine the vehicle has or even that it has an engine.
>
>              Mark
>
>