Hey a loacal salvage guy in my town has a 4.0L in his yard with no wiring, I blew my 4.2L up and can't find one anywhere, i was wondering if I can swap the intake manifold off my 4.2 and put it on the 4.0L and run it like that. If it will fit what kind fo problems will I run into? Jetting, timing and such....

Don't know if this helps, but I am running an 88 Yj 4.2 intake on a 96 4.0 head.
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Hey a loacal salvage guy in my town has a 4.0L in his yard with no wiring, I blew my 4.2L up and can't find one anywhere, i was wondering if I can swap the intake manifold off my 4.2 and put it on the 4.0L and run it like that. If it will fit what kind fo problems will I run into? Jetting, timing and such....
yes its doable with minor modifications. google "monsterslayer jeep", depending on your smog laws you can also go to an aftermarket 4 barrel intake and carb.

Hey a loacal salvage guy in my town has a 4.0L in his yard with no wiring, I blew my 4.2L up and can't find one anywhere, i was wondering if I can swap the intake manifold off my 4.2 and put it on the 4.0L and run it like that. If it will fit what kind fo problems will I run into? Jetting, timing and such....

This will answer your question;

http://jeep.off-road.com/jeep/article/articleDetail.jsp?id=277013