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Discussion Starter · #1 ·
What year 4.0s are a direct swap for my 91 wrangler with a 4.0. I know ill swap my accesories and intake setup and what not. But me finding a 4.0 may be cheaper than a rebuild
 

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Someone will probably chime in to correct me if i'm wrong, but I think the 4.0 went to "H.O." in 92. So anything from any pre 92 4.0 XJ should work, I think the early YJ's had the 4.2 which is usually carb'd.
I hope this helps :thumb:
 

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I have a '91 YJ and its H.O. :thumb:
 

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Discussion Starter · #4 ·
My 1991 says 4.0 high output on the back.
 

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Why just 91-95, if you re use old intake and things I would think 91 and all the way up there was a change in 96 better block, braces on the main caps [less harmonics and less vibration], better heads, I would check into a 96-99. 2000 had bad heads they'd crack!
 

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a lot of 4.0 blocks will work, even from 6 cyl ZJs

91-95 YJ will save a lot of time as you won't have to switch anything else on a yj motor
if its a cherokee motor, the accessories will be different

96 and up also went to OBDII

the head problem started in 99, but was also over exaggerated
 
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