70 javelin wiring

The relay provisions also good for the headlights that make things much better.

No cutting or splicing - same spade terminal connections.

Even put a plastic plate behind so no modifications to the fuse mount, i.e. no new holes to drill.

Only additions to the harness were more grounds.

The problem with making your own harness is buying in small volumes the different colored wires and connectors, cost you more then double.

I have gone to a wrecker and taken a modern harness out of an F150, cut and spliced on connectors, but this is very time consuming and you have to make a new wiring diagram for the spliced colors for future maintenance - just not worth it.

So you can imagine the wire map and color conversion chart I have for my SX4 since it's a marriage of the original Eagle harness and a 94 Grand Cherokee engine bay harness - and I used the Check engine light in the Eagle dash as the MIL lamp for the Jeep computer, among other neat things... cruise control, I had to adapt the Eagle stock switch to operate the Jeep computer as the switch functions are VERY different - a relay, diodes and so on. And electric windows and locks - using stock AMC Eagle stuff but modernizing with relays and making it all compatible with remote entry systems (ground the relay to operate the locks or windows)
Yup - wired many many cars often from scratch or using other harnesses and adding my own touches. 

It's something I actually love doing.
I have also made harnesses for people wanting to put the stock charging systems back in their AMC, among other custom harnesses.