Thought I'd share how I converted to electric 12 guages. Was way easier than I expected! Found some F0rd truck guages at the junkyard, took them apart as shown and they fit perfectly with my GM faces,you just have to notch the needle sweep area with cutters. When you mount finished guage in 5" housing, need to elongate the holes, no big deal. Fits real sweet!
What this does is gives me stock appearing 12v fuel guage, electric temp (use Ford sender), and voltmeter (behind ammeter face). Small white indicator dots on ammeter face optional.
You'll find these F0rd guages come in either swing-left or swing-right so you can match to all the GM apps.
Fun, easy benchtop project, hope this was helpful!
