All sorts of fubar'd up... HELP!?

First xj build.. Started with a 96 xj with the 2.5+ax5. Swapping in a 4.0+ax15. Nothing wants to line up.. Frame horns are from a 4.0 xj, are the bolt holes the same? Trimming in the cab for the stick to poke thru? Having the hardest time trying to find the info I'm looking for. Any help is much appreciated!

I'm looking at the same thing, but instead working on the 2.5. Have everything here to swap in a 4.0/AW4/242 but I can kind of see the differences coming. Share what you find here.

you shouldn't need to trim anything on the tunnel. you might need a different tunnel cover, but I don't think so. I am pretty sure the clutch hyd stuff is the same. you will need lots of elec harness work. the heavy parts should fit pretty easy.

have fun with it

Post pictures when you tear down the core support. Mine looks awfully different, but it also appears to be bolted on, so perhaps it's all easily removed.

I have a '96 with the 4.0/AX15.

If you are willing to put in the effort to take detail pictures of the areas where you are having issues I can try to take comparable pictures of the way mine was built by the factory.

My motor mount situation probably won't be the most helpful since I have switched over to Brown Dogs, but I do still have the original block brackets for the sake of comparison.

I don't know, but would wonder if there might not be a crossmember difference to consider.

I did the same swap in my 87 MJ......there's a cover plate on the trans tunnel inside the cab, different covers for different transmissions. Here's a pic, the AX5 one is on the left, the AX15 on right:



You need to use 4.0 frame horns AND 4.0 motor mounts. The fame horns install in different bolt holes in the frame rails....the threaded holes are there but are not used on the 2.5 version. 2.5 motor mounts look identical to the 4.0 ones, but they're not (4.0 ones are a tad taller). Here's a pic of the 4.0 frame horns installed, see if yours are in the same position:



You will need an AX15 specific trans crossmember.....it has a recessed center section to offset the height difference (Ax5, AW4, and BA10/5 trannys all use the same crossmember, only the AX15 one is different). If you don't use an AX15 crossmember, your shifter linkage will not line up and your cat converter will be kissing the floorboard. Ask me how I know.

Pic of the AX15 crossmember, hard to see but look at the center part where the trans bolts to it:



You also need to move the crossmember back one set of holes on the frame rails. Not sure on your 96, but on my MJ the holes were there but not used. There is a stud on each side that my original crossmember used that I had to knock out to install the new crossmember, it interfered with the fit. Not sure if yours has stud or not, so YMMV.

On the TC linkage, you will need two specific AX15 related parts....the bracket that bolts to the trans tunnel and the short rod that connects the bottom of that part to the range lever on the TC. Parts #14 and 15 in this pic:



HTH,
Jeff