The original Rally Pac had two taped cables from the back:
The clock harness - blue-red (lights), black (power - should have a male bullet), black (ground - should have a ring lug).
The tach harness - blue-red (lights, attaches to the blue-red above), black (goes to the resistance wire to the coil), red (to ignition switch).
There is a feed harness that goes under the dash. It's available, NPD - 10B943-1D, $24.95, and others.
Jim