The voltmeter come with some inulation grommets to keep it from shortin out, I had to use a rattail file to open up the stud mounting holes, this allowed me to mount the voltmeter sure that it would not short out against the cluster.
Back of voltmeter mounted

The negative wire I grounded to the back of the instrument cluster. I mad up a short wire with a plug in terminal and ran it from the positive post to a wiring block that was hot when the key was in either run or accesories. Then I performed the mod to directly connect the positive leads that used to go to the ampmeter. I tested the voltmeter before putting it back in the dash with a known power source and a Flug voltmeter. The gage can be adjusted for accuracy by adjusting the pot on the gage, mine proved to be dead on as it was mounted.

Completed gage.

Well there you go, now I have a working voltmeter in my intrument cluster and have gotten rid of a potential problem with the old Amp gage. Anybody need an Amp gage for a 'Cuda? I have now rebuilt the Tach, Clock, Voltmeter, voltage regulator, and replace the temp gage with a perfect match out of a 86 dodge van.