55.2 Gmc 12 volt with a small block

Trying to see if my temp and ampere gauge work or not. The ampere gauge has two poles. Temp gauge has one very unique pole. Here's a photo - https://flic.kr/p/uwde1B

Is there a way I can bench test them? I have a multi meter but I'm a rookie with it.

I do not know if the gauges were meant for a 12v or 6v system.

And I bought a voltmeter today that I plan on installing in place of the ampere gauge, but I would like to at least see if it works.

1955 GMC 100 Series 2