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my 2.5 $#!& the bed can I keep my aw4 transmission if I put a 4.0 in it if so what year 4.0 will fit and what else do I need wire harness and computer motor mounts ?? I want to keep the 4spd because I just put a new clutch also will my transfer case work with the 4.0 any help would be great forgot mine is also a 4x4 thanx

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The AW4 is an automatic transmission. If you have a 4 speed manual behind a 2.5, it is an AX4. There is no way to mount an AX4 behind a 4 litre, and if there was it wouldn't last a day.


It might be better to look for an 87-90 2.5 to replace yours. Swapping from a 2.5 to a 4.0 is a LOT of work. Radiator mounts and motor mounts have to be removed and new ones welded in. Pretty much EVERYTHING under the hood needs replaced, including wiring harness. With the amount of work involved, there is not much of a difference between swapping in an 87-90 4.0 or going newer (91 through 01 XJ) with an HO engine. Either way you will also have to replace the transmission, transmission cross member and most likely the transfer case (or swap another input shaft into it). I don't know if the driveshafts will still work or not.

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The motor mounts don't need to be welded, they are bolted to the frame. There is no way to retain your flywheel/clutch setup if you plan on going to the 4.0L, plus you'll want to go to an AX15 or NV3550 as the AX4 and AX5 will not survive long behind the 4.0L. If cross members are the same between the AX4 and AW4 while the cross members of the AX5 and AX15 are dropped about an inch lower (ask me how I know...), I'm not sure about the NV3550 though but assuming it's in the same boat as the AX15.


The transfer case will bolt up to an AX4, AX5 and '87-'90 AW4. You will need to swap the input splines or get a new transfer case for AX15, NV3550 and '91-'01 AW4's as they went to 23 spline.


As mvusse said, if you plan on going to a 4.0, you might as well swap in the newer HO setup. But you just might be better off getting another 2.5L.

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