How to hook up elecrical guages

The gauges should come with instuctions, so no worrys there.
Grab yourself new sending units if need be and run new wires to the unit alongside the old wires. Should you need to go through the fire wall, a small grommet should be used for the new hole to be drilled. However, I'm sure theres something there you can go through.

Convolting tube cleans up a compartment nicely and hides any extra wires.
Food for thought.

Lights for the gauges are tapped off a hot wire when the ignition is on (Car running) and cold when off (Car not running) Gounded anywhere to metal. Easy. Back off radio, sheet metal screw etc...