Well, I took a step backwards and pulled the instrument cluster back out after deciding on doing a 3G conversion and reading it is recommended to eliminate the ammeter when doing so or converting it to a volt meter. I saw where someone had put an aftermarket gauge in the stock location, but it had a different face on it. I also saw where I could send it off to have the conversion done to the stock gauge, but with shipping it would be over $50. So, I bought a Sunpro voltmeter on Amazon and put the mechanism in the stock housing, keeping the stock face. Here's the voltmeter for reference: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
After carefully prying the stock face off, I had to modify it by cutting a section out of the bottom so it would slide onto the housing with the aftermarket mechanism in it.
I had to flatten the bottom of the housing between the holes so the aftermarket works would sit flat and file the holes a bit as the posts were just a tad narrower than stock.
I had to shim the bottom of the works with a couple of washers on each side and pieces of Folgers lid (to insulate) to raise it as high as I could b/c the stock face is thicker than the aftermarket one and the needle barely clears after shaving the battery icon and the white indicator lines down.
The aftermarket works was a very tight fit in the stock housing. I had to bend the resistors to get them to clear and make sure the tail of the needle didn't hit the flat section of the housing.
The face snaps on the housing nicely with the notch cut out. I thought about cutting the aftermarket needle off and grafting on the stock needle, but didn't want to take the chance of it falling off.
I had to elongate the holes in the cluster housing slightly. A buddy gave me a cluster from an 82 F150. I swapped the printed circuit onto mine b/c the ammeter circuit was burned on it so I didn't feel as bad cutting it out. You can see remnants of the burned circuit between where I cut it out.
I need to find some paint for the faded stock needles, but after finding a switched hot it should be ready for the 3G.