Which harness would be better???

[Chalky]

So here's a question. I will be rebuilding all the harness' for the new car. By that I mean full strip of tape and wraps and then repair and re-wrap like original having replaced any broken connectors or wires. I have several harnesses in my collection, a couple of 84's and a couple of '86's, one of which came from a car with 32k on the clock.

The car will be running a full '86 engine, exhaust and fuel system and it will continue to run a PE EEC. The only deviations will be the NoS '84 throttle body i have, but i could always swap the TPS connector, and the radio. Am I better of rebuilding one of the '86 harnesses or should I stick with '84 stuff?? Can I use an '84 instrument cluster circuit board with '86 wiring harnesses??

[MikeFleming]

The 86 harness(es) should have less insulation rot. But it's still 25 years old.

There are only minor differences between an 84 an 86 harness.

[brsvo]

If your going through the work replace all the wire you can while your at it. When we did mine we used an 89 NA harness for a doner. Better insulation than the 84's and no turbo heat either. (Till now) 84 SVO harness's were notorius for falling apart!

[Ford Builder]

There is company out there that will build you a brand new harness , all you need to do is lend them a harness to build from, headlights to tailights what ever you want or just the engine harness seeing it gets out side elements .

[runamuk86]

I've had horrible luck with all 84 mustang harness's(2.3 and 5.0). the wire insulation just falls off. 86 seems to be much better and when my car had an electrical fire, i spliced an 86 harness in to repair the damage, as well as any wires that were falling apart. 86 seems to have better insulation. It has held up so much better than the 84 harness.

[Patrick]

Use the green cluster with the 84 harness.
Use the red cluster with the 85-86 harness.

If you mix them up, the charging system won't work.

[JTurbo]

Hey Pat, care to expand the differences on this?

Thanks - JT

[Patrick]

The early (84) cluster has a green circuit ribbon on the back side of the cluster. The 85-86 has a red one. The contact where the harness connector completes the charge circuit is located differently from the green version to the red version.