Using 67 cuda dash in a 70 dart

You can use the Dart wiring harness. You can even use the Dart’s under dash wiring, even if the Dart has a non-rallye dash. Some of the wires need to be traded around in the plug for the gauge cluster, but it’s pretty easy. Most of the wire colors are the same or similar, just some of the positions in the plug changed.

I used my ‘74 Duster’s original harness when I converted it over to a rallye dash. Mostly just moving wires around in the plug, although that conversion does need an extra 3 wire plug added in.