4.0 swap, have a question

okay, so half way through the replacement of heads on my 2.9, I decided to say screw it and swap a 4.0 instead.
But.. Swapping Dashes is just not a option.. I want to retain my gen 1 dash, to keep the interior as original as possible..
I seen that it has been done, but don't remember the user that did it

Has anyone else done this swap while keeping the original dash intact?
Or does anyone have any suggestions or comments to help me with this?

I kept my original 87 dash when i swapped in the 4.0, its doable but requires some wire splicing. My tach still doesn't work right, haven't figured that one out. Other than that, its complete functional. Used an engine harness and power distribution from a 90 ranger.

any other suggestions/advice on this?
Also, if i use a motor from an explorer, what would be easier, using the explorer harness or finding one from a ranger?

i bought a running explorer for $400, but i dont want the auto tranny.
i had an explorer with an auto and never again.

so i was just thinking about picking up a tranny from a manual ranger along with that harness and computer so it would be from a 4.0, manual, 4x4.

Also, if i find a tranny from a 4.0 will that bolt up to my stock tcase?

I've done the swap too. I also deleted all of the "extra" wiring from the Explorer harness. (Daytime Running Lights, Fog lights, anti-lock brakes, Etc.) Removing the extra wires was a complete waste of time. There weren't that many and it made the swap take an extra week.

In the '87 keeping the stock dash, the differences in the Explorer harness and the Ranger harness are minimal. (Brake/Tail lights and power for options the Ranger never had.)

To help simplify things, whatever vehicle you get the wiring harness from, take both sides of the Big White Plug. (Under-hood and under-dash) Make sure you leave enough extra wire from under the dash to reconnect all of them.

Make sure the harness matches the ECU you want to use. Some of them had 2 vs 1 O2 sensors and wiring for sequential injection rather than batch fire. In general, take it all from one vehicle and you should be fine.

Don't remove the stock light wiring from your truck! It'll stay the same.

The computer and engine harness will plug in just like they were in the donor. The only wires that need spliced are at the Big White Plug. (That's why you have both sides of it. You can just work with the short piece and connect it to your original dash harness right on the driver's side fender.)

Yes the 4.0 transmission can be connected to your transfer case. The 2.9 transmission/flywheel/clutch can even be bolted to the 4.0 if you want. (I did but I don't recommend it because the clutch slips FAR to easily. I've got the 4.0 M50D sitting in the driveway waiting for me to get time to put it in now.)

The wiring for the transmission unplugs from the rest of the harness and makes converting an auto harness to manual trivial.

Kunar: Does your tach read WAY too high? Like 3000 at idle. Mine did that and I had to ground another wire on the gauge itself to correct the reading.

Noob is pretty much right on. I didn't use the big white plug, instead I cut up my 2.9 harness and used the 3 or 4 smaller plugs. Still got to the same place though. Other than that, all very good info there, señor.

As far as the tach goes, it reads 1.5x what it should. Live data from the computer shows correct info. I have a spare cluster I can take a look at, maybe you're onto something. Thanks for the heads up.

I went a completely different route from these guys and took an 89 dash harness and repinned it to plug into my 87 dash. It was not hard, except for the cluster. Most of the other stuff was really straight forward.

I'm not sure what you guys are talking about with the tach. Mine reads more or less correctly, but seems to top out at 2000 RPM, even though I can hear the engine keep winding up and I keep accelerating.

now here's some good info!