[ray_mcavoy]

On the voltmeter, the terminal that's off to the left (as shown in your photo) is the one that's connected to the voltage you want to measure. The terminal that's up toward the top/center is ground. And the terminal over on the right is an intermediate connection between the ceramic resistor and the internal meter coil (don't make any external connections to that post).

On the oil pressure gauge, the terminal that's off to the left is the one that gets connected to the sending unit on the engine. The terminal that's down toward the bottom/center is ground. And the terminal over on the right is +12V.