I started with a 2’ Sunpro voltmeter from Autozone. Costs something like 20 bucks.
http://www.autozone.com/autozone/ac...&fromString=search&itemIdentifier=953313_0_0_
The key is that this has a simple needle that pivots from a point like the ammeter.
You remove the innards, which is not elegantly done because it’s pressed together. So I ended up breaking the glass, which isn’t used anyway. Then you save the little post insulators and stuff.
If you look closely it has a face that is held on with small screws. Remove these and you can install a face that duplicates the shape of the old ammeter. To do that you need to make up a new face with a little graphics. I used photographs of both the old ammeter and the new voltmeter (before I removed its face), placed them both in my favorite drafting application and created a voltmeter face that replicated the location and sweep of the ammeter. (You establish the location of the pivot point on the old gauge and make a voltmeter sweep that fits in the same location as the old ammeter sweep.) At this point you draft up the outline of the old face and use it to draft the outline of the new face. Then draft on the numbers in the appropriate places. Then print the new face on stiff photo paper. I was going to mount it on a piece of metal, but the paper is so stiff that it can be used like a thin piece of metal, held on with the screws and all.
It turns out that the depth of the Sunpro is exactly right, so all you need to do besides making the new face, is make up a small sheet metal plate to attach it to, using the old ammeter backing plate (the part that actually bolts to the gauge cluster back) as a pattern.
I installed a Painless harness, so I was able to use one of the key-on 12 volt fused circuits for the power. The ground wire went to one of the dash screws where I had grounded other wires for the new harness.
It sounds more complicated than it is. This is a nice project for a cold, snowy day in between real projects.
Here is a short sequence that shows the process of doing up the face.