97 2500 Van Gauges problem

Can't get any gauge except the gas gauge to work on my 1997 Dodge 2500 conversion van with a 3.9 engine. Have replaced the gauge fuse, which was missing but no response. Have been told that a bad ground can cause the problem, but don't know where to start looking for the right ground (fuse box, under the dash??). Thanks.

The missing ground would be the one at the right rear of the engine that runs from the passenger head to the body. Notice how the gauges that don't work are all engine mounted (oil, temp, alternator) while the only working one (fuel) is not engine mounted. This gives credibility to an engine to body ground being lost.