We got a new engine wiring harness, new printed circuit, and the original gauges.

Running a brown wire from the negative post on hte back of hte tach to the negative coil didn't work, nothing has worked, it has no reaction, but nothing appears burnt out or broken.

Can anyone tell us the exact hookup of hte tach, if what wires we need to run where etc.

The tach needs power, ground and the brown wire mentioned to the coil -. The power comes from the pink wire in the cluster connector. The ground is the cluster ground wire from the dash harness, black with ring lug attached to a screw on the cluster back.