Swapping engine and tranny

[BIGSLVRXJ]

It's very possible I'm going to get a 1991 parts XJ that has a good engine and tranny and I would like to swap both into my 1990. The 91 has a manual tranny and 4.0HO. Mine has the 4.0LO and the AW4. What will I have to change ECU/Wiring-wise to make this work?

[Dr. Dyno]

Get the PCM and the TPS that come with the '91 manual XJ and you should be set. You'll also need the clutch system, slave cylinder, piping, fluid reservoir, and clutch/brake pedals. The brake pedal is smaller on a manual tranny vehicle.

[BIGSLVRXJ]

Is that really all that has to be done? For swapping both the engine and tranny?

[oldmustangjunkie]

A few things have to be changed to make it work, but the swap doesn't seem too bad...
http://www.off-road.com/jeep/cherokee/99/09_sept/engswap/engswap.html

[75SV1]

I'm doing something simular, an '88 Comanche. Swapping in '95 electronics, NV 3550. Mine is a manul already though. You are switching from a Renix motor to a HO. The drive shafts should be of different lenghts. You might need to swap the transmission cross member and tranny mount. The instrument panels are different. Mainly, the speedo on the 90 is mechanical and its electronic on the 91. If you are swapping this out, I'd get the full gauge instrument panel, if you don't have one already. You should swap in the 91's wiring harneses. The EMC on the 91 is up be the air intake box. Its in the cabin on the 90. You should also swap the radiator/cooling system. The 87-90 is a closed system and the 91-up are open. There is some wiring differences between the cooling systems. If 4WD, then keep the transfer case attached from the 91. The input shaft splines are different.
Tom