[ray_mcavoy]

The temperature and fuel gauges can be tested by hooking them up to +12V power and ground (cluster case) and using resistors to simulate the sending units. Connecting the fuel gauge sending unit terminal directly to ground (0Ω) should make it read empty. Connecting it to ground through a 15Ω resistor should make it read half, and through a 30Ω should make it read full. Connecting the temp gauge sending unit terminal to ground through a 500Ω (or higher) resistor should make it read on the cold end of the scale. And something around 80Ω should bring it up to the hot side.

The battery gauge (ammeter) can be tested with a 1.5V battery (such as a AA or AAA). Connect it directly across the two terminals and the needle should swing in one direction. Reverse the polarity and the needle should swing in the other direction.

The oil pressure gauge can be tested by hooking it up to a compressed air source with an adjustable pressure regulator (preferably one with it's own gauge so you can see if the pressure readings match).