4.2 or 4.0 aahhhh!!!

[1 out of 2]

Hey,
This is my first post of many I believe, so I need help making the better choice from anyone who knows whats involved/cost. I have an 89yj 4.2 5spd and a 91yj 4.0 auto. Now here's my issue, the 91 has a 6" suspension lift with a 3" body lift and 36" rubbers. 4" front/rear tube bumpers and other small accesories. The 89 is bone stock except for some stainless checker plate here and there. I paid $2000 for the 91 and $500+case of beer for the 89. The 91's tub or (inside floor) was completely replaced but, the under floor or (underside) is completely rotted and definately unrepairable. The frame is solid except for the rear cross member at the bumper. No repairs are needed from the frame to the ground. The 4.0 runs well, the transmission is perfect but the transfer case won't go into neutral or 4low. Axles are stock but good.
***This is alot to read I'm sorry but I'm venting all of this now***
The 89 however underneath is much better and the tub is just alittle surface rusty (common jeep rot) but much more solid. It has 233,000kms and has that all to familiar ignition problem and that ****ty carb. The 5spd/clutch are excellent and the transfer case works well too.
So here's what I'm asking> Should I swap bodies or engines and transmissions? What's involved with both? I am very mechanically inclined and know how much work it will be either way it goes! I hope someone has thought about this and or has done this before. I can't save both my babies but I'll try build the best of the two as one. Please HELP ME!!!!!

 

[Sparky-Watts]

First of all, lemme be the first to give you a big "Welcome to Jeepz!" Hope you stick around, it's always good to have new members join up and become old members.

As for your dilemma, I probably won't be much help. My guess is that it may be easier to swap engines, but I'm not sure what's involved in swapping a 4.0 with a 4.2. Sorry. Anyway, there are lots of great minds here that will help you make the right decision for you.

Again, Welcome to the "Z" and good luck with your problem!

 

[redrooster]

I would put the 89 body on the 91 drivetrain. The hardest part will be labeling and removing the wiring harness. Removing the body will give you easy access to the frame where you can get on it with a wire wheel and POR 15 prior to installing the 89 body. Might want to POR 15 the underside of the 89 tub while you're at it.
Oh yeah, start lubricating a few days prior with some penetrating oil and let it soak in to your body mount bolts.

 

[mud4feet]

I would put the 89 body on the 91 drivetrain. The hardest part will be labeling and removing the wiring harness. Removing the body will give you easy access to the frame where you can get on it with a wire wheel and POR 15 prior to installing the 89 body. Might want to POR 15 the underside of the 89 tub while you're at it.
Oh yeah, start lubricating a few days prior with some penetrating oil and let it soak in to your body mount bolts.

:agree:

And.......you could cut down a bit on that 3" body lift.:shock:

 

[1 out of 2]

Thanks for your input on my issue. I don't know too much about these engines, will the 89 5spd bolt up to the 4.0 with no headechs? I've actually have been soaking many bolts in both vehicles to prepare for this BIG job ahead! Thanks again, Maybe in the future I'll go big V8.

 

[redrooster]

The transmission should bolt up without problems, but you will have to accomodate the crank position sensor.
I personally would run the auto anyway. Those autos were slightly stouter than the 5 speed. They are also user friendly in the woods. Like TC said, "point and shoot."
If you run the auto in the 89, make sure you save the pedal set from the 91.

 

[TerryMason]

I put a YJ tub on my CJ, and I'll tell you those things are heavy! It took 4 of us to pick it up and move it. Make sure to take the shifter off, instead of lifting the body over..

 

[redrooster]

I put a YJ frame under my CJ. There were just two of us. You should have seen the OSHA unapproved use of jackstands, tubing and an engine hoist going on that day. Actually it was pretty safe. We raised the body with an engine hoist an end at a time. Then slid a long pc of tube under each end and let the tube rest on jackstands out to the side. Slid the frame under then jacked it into place and supported it with blocks. Then we pulled the tubes and lowered the body down into place.
It will be much easier with a rolling chassis and 3 friends.